diff --git a/CHANGELOG.md b/CHANGELOG.md
index 173148b..6e2be24 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,21 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 # [unreleased]
 
+## Changed
+
+- `serde` support is now optional and behind the `serde` feature
+- `PusTcSecondaryHeaderT` trait renamed to `GenericPusTcSecondaryHeader`
+- `PusTmSecondaryHeaderT` trait renamed to `GenericPusTmSecondaryHeader`
+- `SpHeader`: Former `tc` and `tm` methods now named `tc_unseg` and `tm_unseg`.
+  Former `new` method now called `new_from_single_fields`
+
+## Added
+
+- `serde` `Serialize` and `Deserialize` added to all types
+- Added `const` constructors for `PacketId`, `PacketSeqCtrl` and
+  `SpHeader`
+- Added `PartialEq` and `Eq` `derive`s to `CdsShortTimeProvider`
+
 # [v0.3.1] 03.12.2022
 
 - Small fix for faulty docs.rs build
diff --git a/Cargo.toml b/Cargo.toml
index bec8709..6058e82 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -18,6 +18,7 @@ delegate = "0.8"
 
 [dependencies.serde]
 version = "1.0"
+optional = true
 default-features = false
 features = ["derive"]
 
@@ -33,8 +34,9 @@ default-features = false
 version = "1.0"
 
 [features]
-default = ["std"]
+default = ["std", "dep:serde"]
 std = ["chrono/std", "chrono/clock", "alloc"]
+serde = ["chrono/serde"]
 alloc = ["postcard/alloc"]
 
 [package.metadata.docs.rs]
diff --git a/README.md b/README.md
index 1c53c87..a4420c7 100644
--- a/README.md
+++ b/README.md
@@ -33,6 +33,7 @@ Default features:
  - [`alloc`](https://doc.rust-lang.org/alloc/): Enables features which operate on containers
    like [`alloc::vec::Vec`](https://doc.rust-lang.org/beta/alloc/vec/struct.Vec.html).
    Enabled by the `std` feature.
+ - [`serde`](https://serde.rs/): Adds `serde` support for most types by adding `Serialize` and `Deserialize` `derive`s
 
 # Examples
 
diff --git a/src/ecss.rs b/src/ecss.rs
index a3cfb42..06e40f4 100644
--- a/src/ecss.rs
+++ b/src/ecss.rs
@@ -4,6 +4,7 @@ use crate::{ByteConversionError, CcsdsPacket, SizeMissmatch};
 use core::fmt::Debug;
 use core::mem::size_of;
 use crc::{Crc, CRC_16_IBM_3740};
+#[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
 pub type CrcType = u16;
@@ -13,7 +14,8 @@ pub const CRC_CCITT_FALSE: Crc<u16> = Crc::<u16>::new(&CRC_16_IBM_3740);
 pub const CCSDS_HEADER_LEN: usize = size_of::<crate::zc::SpHeader>();
 
 /// All PUS versions. Only PUS C is supported by this library.
-#[derive(PartialEq, Eq, Copy, Clone, Serialize, Deserialize, Debug)]
+#[derive(PartialEq, Eq, Copy, Clone, Debug)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum PusVersion {
     EsaPus = 0,
     PusA = 1,
@@ -35,6 +37,7 @@ impl TryFrom<u8> for PusVersion {
 }
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum PacketTypeCodes {
     Boolean = 1,
     Enumerated = 2,
@@ -51,6 +54,7 @@ pub enum PacketTypeCodes {
 }
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum PusError {
     VersionNotSupported(PusVersion),
     IncorrectCrc(u16),
@@ -212,6 +216,7 @@ impl ToBeBytes for u64 {
 }
 
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct GenericEcssEnumWrapper<TYPE> {
     val: TYPE,
 }
diff --git a/src/lib.rs b/src/lib.rs
index f9b8840..d8da91e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -27,18 +27,20 @@
 //!  - [`alloc`](https://doc.rust-lang.org/alloc/): Enables features which operate on containers
 //!     like [`alloc::vec::Vec`](https://doc.rust-lang.org/beta/alloc/vec/struct.Vec.html).
 //!     Enabled by the `std` feature.
+//!  - [`serde`](https://serde.rs/): Adds `serde` support for most types by adding `Serialize` and
+//!    `Deserialize` `derive`s
 //!
 //! ## Module
 //!
 //! This module contains helpers and data structures to generate Space Packets according to the
 //! [CCSDS 133.0-B-2](https://public.ccsds.org/Pubs/133x0b2e1.pdf). This includes the
-//! [SpHeader] class to generate the Space Packet Header component common to all space packets
+//! [SpHeader] class to generate the Space Packet Header component common to all space packets.
 //!
 //! ## Example
 //!
 //! ```rust
 //! use spacepackets::SpHeader;
-//! let sp_header = SpHeader::tc(0x42, 12, 0).expect("Error creating SP header");
+//! let sp_header = SpHeader::tc_unseg(0x42, 12, 0).expect("Error creating SP header");
 //! println!("{:?}", sp_header);
 //! ```
 #![no_std]
@@ -51,6 +53,7 @@ extern crate std;
 use crate::ecss::CCSDS_HEADER_LEN;
 use delegate::delegate;
 
+#[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
 pub mod ecss;
@@ -62,12 +65,14 @@ pub const MAX_APID: u16 = 2u16.pow(11) - 1;
 pub const MAX_SEQ_COUNT: u16 = 2u16.pow(14) - 1;
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct SizeMissmatch {
     pub found: usize,
     pub expected: usize,
 }
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum ByteConversionError {
     /// The passed slice is too small. Returns the passed slice length and expected minimum size
     ToSliceTooSmall(SizeMissmatch),
@@ -78,7 +83,8 @@ pub enum ByteConversionError {
     ZeroCopyFromError,
 }
 
-#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Copy, Clone)]
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum PacketType {
     Tm = 0,
     Tc = 1,
@@ -100,7 +106,8 @@ pub fn packet_type_in_raw_packet_id(packet_id: u16) -> PacketType {
     PacketType::try_from((packet_id >> 12) as u8 & 0b1).unwrap()
 }
 
-#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Copy, Clone)]
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum SequenceFlags {
     ContinuationSegment = 0b00,
     FirstSegment = 0b01,
@@ -124,21 +131,57 @@ impl TryFrom<u8> for SequenceFlags {
     }
 }
 
-#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Copy, Clone)]
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct PacketId {
     pub ptype: PacketType,
     pub sec_header_flag: bool,
     apid: u16,
 }
 
-impl PacketId {
-    pub fn new(ptype: PacketType, sec_header_flag: bool, apid: u16) -> Option<PacketId> {
-        let mut pid = PacketId {
-            ptype,
-            sec_header_flag,
+impl Default for PacketId {
+    fn default() -> Self {
+        PacketId {
+            ptype: PacketType::Tm,
+            sec_header_flag: false,
             apid: 0,
-        };
-        pid.set_apid(apid).then_some(pid)
+        }
+    }
+}
+
+impl PacketId {
+    pub const fn const_tc(sec_header: bool, apid: u16) -> Self {
+        Self::const_new(PacketType::Tc, sec_header, apid)
+    }
+
+    pub const fn const_tm(sec_header: bool, apid: u16) -> Self {
+        Self::const_new(PacketType::Tm, sec_header, apid)
+    }
+
+    pub fn tc(sec_header: bool, apid: u16) -> Option<Self> {
+        Self::new(PacketType::Tc, sec_header, apid)
+    }
+
+    pub fn tm(sec_header: bool, apid: u16) -> Option<Self> {
+        Self::new(PacketType::Tm, sec_header, apid)
+    }
+
+    pub const fn const_new(ptype: PacketType, sec_header: bool, apid: u16) -> Self {
+        if apid > MAX_APID {
+            panic!("APID too large");
+        }
+        PacketId {
+            ptype,
+            sec_header_flag: sec_header,
+            apid,
+        }
+    }
+
+    pub fn new(ptype: PacketType, sec_header_flag: bool, apid: u16) -> Option<PacketId> {
+        if apid > MAX_APID {
+            return None;
+        }
+        Some(PacketId::const_new(ptype, sec_header_flag, apid))
     }
 
     /// Set a new Application Process ID (APID). If the passed number is invalid, the APID will
@@ -171,27 +214,39 @@ impl From<u16> for PacketId {
     }
 }
 
-#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Copy, Clone)]
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct PacketSequenceCtrl {
     pub seq_flags: SequenceFlags,
     seq_count: u16,
 }
 
 impl PacketSequenceCtrl {
-    /// Returns [None] if the passed sequence count exceeds [MAX_SEQ_COUNT]
-    pub fn new(seq_flags: SequenceFlags, seq_count: u16) -> Option<PacketSequenceCtrl> {
-        let mut psc = PacketSequenceCtrl {
+    /// const variant of [PacketSequenceCtrl::new], but panics if the sequence count exceeds
+    /// [MAX_SEQ_COUNT].
+    const fn const_new(seq_flags: SequenceFlags, seq_count: u16) -> PacketSequenceCtrl {
+        if seq_count > MAX_SEQ_COUNT {
+            panic!("Sequence count too large");
+        }
+        PacketSequenceCtrl {
             seq_flags,
-            seq_count: 0,
-        };
-        psc.set_seq_count(seq_count).then_some(psc)
+            seq_count,
+        }
+    }
+
+    /// Returns [None] if the passed sequence count exceeds [MAX_SEQ_COUNT].
+    pub fn new(seq_flags: SequenceFlags, seq_count: u16) -> Option<PacketSequenceCtrl> {
+        if seq_count > MAX_SEQ_COUNT {
+            return None;
+        }
+        Some(PacketSequenceCtrl::const_new(seq_flags, seq_count))
     }
     pub fn raw(&self) -> u16 {
         ((self.seq_flags as u16) << 14) | self.seq_count
     }
 
     /// Set a new sequence count. If the passed number is invalid, the sequence count will not be
-    /// set and false will be returned. The maximum allowed value for the 14-bit field is 16383
+    /// set and false will be returned. The maximum allowed value for the 14-bit field is 16383.
     pub fn set_seq_count(&mut self, ssc: u16) -> bool {
         if ssc > MAX_SEQ_COUNT {
             return false;
@@ -232,7 +287,7 @@ macro_rules! sph_from_other {
 const SSC_MASK: u16 = 0x3FFF;
 const VERSION_MASK: u16 = 0xE000;
 
-/// Generic trait to access fields of a CCSDS space packet header according to CCSDS 133.0-B-2
+/// Generic trait to access fields of a CCSDS space packet header according to CCSDS 133.0-B-2.
 pub trait CcsdsPacket {
     fn ccsds_version(&self) -> u8;
     fn packet_id(&self) -> PacketId;
@@ -246,7 +301,7 @@ pub trait CcsdsPacket {
     }
 
     /// Retrieve 13 bit Packet Identification field. Can usually be retrieved with a bitwise AND
-    /// of the first 2 bytes with 0x1FFF
+    /// of the first 2 bytes with 0x1FFF.
     #[inline]
     fn packet_id_raw(&self) -> u16 {
         self.packet_id().raw()
@@ -257,8 +312,8 @@ pub trait CcsdsPacket {
         self.psc().raw()
     }
 
+    /// Retrieve Packet Type (TM: 0, TC: 1).
     #[inline]
-    /// Retrieve Packet Type (TM: 0, TC: 1)
     fn ptype(&self) -> PacketType {
         // This call should never fail because only 0 and 1 can be passed to the try_from call
         self.packet_id().ptype
@@ -275,13 +330,13 @@ pub trait CcsdsPacket {
     }
 
     /// Retrieve the secondary header flag. Returns true if a secondary header is present
-    /// and false if it is not
+    /// and false if it is not.
     #[inline]
     fn sec_header_flag(&self) -> bool {
         self.packet_id().sec_header_flag
     }
 
-    /// Retrieve Application Process ID
+    /// Retrieve Application Process ID.
     #[inline]
     fn apid(&self) -> u16 {
         self.packet_id().apid
@@ -309,16 +364,18 @@ pub trait CcsdsPrimaryHeader {
     ) -> Self;
 }
 
-/// Space Packet Primary Header according to CCSDS 133.0-B-2
+/// Space Packet Primary Header according to CCSDS 133.0-B-2.
 ///
 /// # Arguments
 ///
-/// * `version` - CCSDS version field, occupies the first 3 bits of the raw header
+/// * `version` - CCSDS version field, occupies the first 3 bits of the raw header. Will generally
+///    be set to 0b000 in all constructors provided by this crate.
 /// * `packet_id` - Packet Identifier, which can also be used as a start marker. Occupies the last
 ///    13 bits of the first two bytes of the raw header
 /// * `psc` - Packet Sequence Control, occupies the third and fourth byte of the raw header
 /// * `data_len` - Data length field occupies the fifth and the sixth byte of the raw header
-#[derive(serde::Serialize, serde::Deserialize, Debug, PartialEq, Eq, Copy, Clone)]
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct SpHeader {
     pub version: u8,
     pub packet_id: PacketId,
@@ -327,55 +384,94 @@ pub struct SpHeader {
 }
 
 impl Default for SpHeader {
+    /// The default function sets the sequence flag field to [SequenceFlags::Unsegmented]. The data
+    /// length field is set to 1, which denotes an empty space packets.
     fn default() -> Self {
         SpHeader {
             version: 0,
-            packet_id: PacketId {
-                ptype: PacketType::Tm,
-                apid: 0,
-                sec_header_flag: false,
-            },
+            packet_id: PacketId::default(),
             psc: PacketSequenceCtrl {
                 seq_flags: SequenceFlags::Unsegmented,
                 seq_count: 0,
             },
-            data_len: 0,
+            data_len: 1,
         }
     }
 }
+
 impl SpHeader {
-    /// Create a new Space Packet Header instance which can be used to create generic
-    /// Space Packets. This will return [None] if the APID or sequence count argument
-    /// exceed [MAX_APID] or [MAX_SEQ_COUNT] respectively.
-    pub fn new(
+    pub const fn new(packet_id: PacketId, psc: PacketSequenceCtrl, data_len: u16) -> Self {
+        Self {
+            version: 0,
+            packet_id,
+            psc,
+            data_len,
+        }
+    }
+
+    /// const variant of the [SpHeader::new_fron_single_fields] function. Panics if the passed
+    /// APID exceeds [MAX_APID] or the passed packet sequence count exceeds [MAX_SEQ_COUNT].
+    const fn const_new_from_single_fields(
         ptype: PacketType,
         sec_header: bool,
         apid: u16,
+        seq_flags: SequenceFlags,
+        seq_count: u16,
+        data_len: u16,
+    ) -> Self {
+        if seq_count > MAX_SEQ_COUNT {
+            panic!("Sequence count is too large");
+        }
+        if apid > MAX_APID {
+            panic!("APID is too large");
+        }
+        Self {
+            psc: PacketSequenceCtrl::const_new(seq_flags, seq_count),
+            packet_id: PacketId::const_new(ptype, sec_header, apid),
+            data_len,
+            version: 0,
+        }
+    }
+
+    /// Create a new Space Packet Header instance which can be used to create generic
+    /// Space Packets. This will return [None] if the APID or sequence count argument
+    /// exceed [MAX_APID] or [MAX_SEQ_COUNT] respectively. The version field is set to 0b000.
+    pub fn new_from_single_fields(
+        ptype: PacketType,
+        sec_header: bool,
+        apid: u16,
+        seq_flags: SequenceFlags,
         seq_count: u16,
         data_len: u16,
     ) -> Option<Self> {
         if seq_count > MAX_SEQ_COUNT || apid > MAX_APID {
             return None;
         }
-        let mut header = SpHeader::default();
-        header.packet_id.sec_header_flag = sec_header;
-        header.packet_id.apid = apid;
-        header.packet_id.ptype = ptype;
-        header.psc.seq_count = seq_count;
-        header.data_len = data_len;
-        Some(header)
+        Some(SpHeader::const_new_from_single_fields(
+            ptype, sec_header, apid, seq_flags, seq_count, data_len,
+        ))
     }
 
-    /// Helper function for telemetry space packet headers. The packet type  field will be
-    /// set accordingly.
-    pub fn tm(apid: u16, seq_count: u16, data_len: u16) -> Option<Self> {
-        Self::new(PacketType::Tm, false, apid, seq_count, data_len)
+    /// Helper function for telemetry space packet headers. The packet type field will be
+    /// set accordingly. The secondary header flag field is set to false.
+    pub fn tm(apid: u16, seq_flags: SequenceFlags, seq_count: u16, data_len: u16) -> Option<Self> {
+        Self::new_from_single_fields(PacketType::Tm, false, apid, seq_flags, seq_count, data_len)
     }
 
-    /// Helper function for telecommand space packet headers. The packet type  field will be
-    /// set accordingly.
-    pub fn tc(apid: u16, seq_count: u16, data_len: u16) -> Option<Self> {
-        Self::new(PacketType::Tc, false, apid, seq_count, data_len)
+    /// Helper function for telemetry space packet headers. The packet type field will be
+    /// set accordingly. The secondary header flag field is set to false.
+    pub fn tc(apid: u16, seq_flags: SequenceFlags, seq_count: u16, data_len: u16) -> Option<Self> {
+        Self::new_from_single_fields(PacketType::Tc, false, apid, seq_flags, seq_count, data_len)
+    }
+
+    /// Variant of [SpHeader::tm] which sets the sequence flag field to [SequenceFlags::Unsegmented]
+    pub fn tm_unseg(apid: u16, seq_count: u16, data_len: u16) -> Option<Self> {
+        Self::tm(apid, SequenceFlags::Unsegmented, seq_count, data_len)
+    }
+
+    /// Variant of [SpHeader::tc] which sets the sequence flag field to [SequenceFlags::Unsegmented]
+    pub fn tc_unseg(apid: u16, seq_count: u16, data_len: u16) -> Option<Self> {
+        Self::tc(apid, SequenceFlags::Unsegmented, seq_count, data_len)
     }
 
     //noinspection RsTraitImplementation
@@ -541,23 +637,75 @@ pub mod zc {
     sph_from_other!(SpHeader, crate::SpHeader);
 }
 
-#[cfg(test)]
+#[cfg(all(test, feature = "std"))]
 mod tests {
-    #[cfg(feature = "std")]
+    #[cfg(feature = "serde")]
     use crate::CcsdsPrimaryHeader;
-    use crate::SpHeader;
     use crate::{
         packet_type_in_raw_packet_id, zc, CcsdsPacket, PacketId, PacketSequenceCtrl, PacketType,
-        SequenceFlags,
     };
+    use crate::{SequenceFlags, SpHeader};
     use alloc::vec;
-    #[cfg(not(feature = "std"))]
-    use num::pow;
-    #[cfg(feature = "std")]
     use num_traits::pow;
-    use postcard::from_bytes;
-    #[cfg(feature = "alloc")]
-    use postcard::to_allocvec;
+    #[cfg(feature = "serde")]
+    use postcard::{from_bytes, to_allocvec};
+
+    const CONST_SP: SpHeader = SpHeader::new(
+        PacketId::const_tc(true, 0x36),
+        PacketSequenceCtrl::const_new(SequenceFlags::ContinuationSegment, 0x88),
+        0x90,
+    );
+
+    const PACKET_ID_TM: PacketId = PacketId::const_tm(true, 0x22);
+
+    #[test]
+    fn verify_const_packet_id() {
+        assert_eq!(PACKET_ID_TM.apid(), 0x22);
+        assert_eq!(PACKET_ID_TM.sec_header_flag, true);
+        assert_eq!(PACKET_ID_TM.ptype, PacketType::Tm);
+        let const_tc_id = PacketId::const_tc(true, 0x23);
+        assert_eq!(const_tc_id.ptype, PacketType::Tc);
+    }
+
+    #[test]
+    fn test_default_packet_id() {
+        let id_default = PacketId::default();
+        assert_eq!(id_default.ptype, PacketType::Tm);
+        assert_eq!(id_default.apid, 0x000);
+        assert_eq!(id_default.sec_header_flag, false);
+    }
+
+    #[test]
+    fn test_packet_id_ctors() {
+        let packet_id = PacketId::new(PacketType::Tc, true, 0x1ff);
+        assert!(packet_id.is_some());
+        let packet_id = packet_id.unwrap();
+        assert_eq!(packet_id.apid(), 0x1ff);
+        assert_eq!(packet_id.ptype, PacketType::Tc);
+        assert_eq!(packet_id.sec_header_flag, true);
+        let packet_id_tc = PacketId::tc(true, 0x1ff);
+        assert!(packet_id_tc.is_some());
+        let packet_id_tc = packet_id_tc.unwrap();
+        assert_eq!(packet_id_tc, packet_id);
+        let packet_id_tm = PacketId::tm(true, 0x2ff);
+        assert!(packet_id_tm.is_some());
+        let packet_id_tm = packet_id_tm.unwrap();
+        assert_eq!(packet_id_tm.sec_header_flag, true);
+        assert_eq!(packet_id_tm.ptype, PacketType::Tm);
+        assert_eq!(packet_id_tm.apid, 0x2ff);
+    }
+
+    #[test]
+    fn verify_const_sp_header() {
+        assert_eq!(CONST_SP.sec_header_flag(), true);
+        assert_eq!(CONST_SP.apid(), 0x36);
+        assert_eq!(
+            CONST_SP.sequence_flags(),
+            SequenceFlags::ContinuationSegment
+        );
+        assert_eq!(CONST_SP.seq_count(), 0x88);
+        assert_eq!(CONST_SP.data_len, 0x90);
+    }
 
     #[test]
     fn test_seq_flag_helpers() {
@@ -640,9 +788,9 @@ mod tests {
     }
 
     #[test]
-    #[cfg(feature = "std")]
+    #[cfg(feature = "serde")]
     fn test_serde_sph() {
-        let sp_header = SpHeader::tc(0x42, 12, 0).expect("Error creating SP header");
+        let sp_header = SpHeader::tc_unseg(0x42, 12, 0).expect("Error creating SP header");
         assert_eq!(sp_header.ccsds_version(), 0b000);
         assert!(sp_header.is_tc());
         assert!(!sp_header.sec_header_flag());
@@ -664,7 +812,7 @@ mod tests {
         assert_eq!(sp_header.ccsds_version(), 0b000);
         assert_eq!(sp_header.data_len, 0);
 
-        let sp_header = SpHeader::tm(0x7, 22, 36).expect("Error creating SP header");
+        let sp_header = SpHeader::tm_unseg(0x7, 22, 36).expect("Error creating SP header");
         assert_eq!(sp_header.ccsds_version(), 0b000);
         assert!(sp_header.is_tm());
         assert!(!sp_header.sec_header_flag());
@@ -695,28 +843,69 @@ mod tests {
     }
 
     #[test]
-    fn test_sp_header_setters() {
-        let mut sp_header = SpHeader::tc(0x42, 12, 0).expect("Error creating SP header");
-        assert_eq!(sp_header.apid(), 0x42);
+    fn test_setters() {
+        let sp_header = SpHeader::tc(0x42, SequenceFlags::Unsegmented, 25, 0);
+        assert!(sp_header.is_some());
+        let mut sp_header = sp_header.unwrap();
         sp_header.set_apid(0x12);
         assert_eq!(sp_header.apid(), 0x12);
-
         sp_header.set_sec_header_flag();
         assert!(sp_header.sec_header_flag());
         sp_header.clear_sec_header_flag();
         assert!(!sp_header.sec_header_flag());
-        sp_header.set_seq_count(0x45);
-        assert_eq!(sp_header.seq_count(), 0x45);
         assert_eq!(sp_header.ptype(), PacketType::Tc);
         sp_header.set_packet_type(PacketType::Tm);
         assert_eq!(sp_header.ptype(), PacketType::Tm);
+        sp_header.set_seq_count(0x45);
+        assert_eq!(sp_header.seq_count(), 0x45);
+    }
+
+    #[test]
+    fn test_tc_ctor() {
+        let sp_header = SpHeader::tc(0x42, SequenceFlags::Unsegmented, 25, 0);
+        assert!(sp_header.is_some());
+        let sp_header = sp_header.unwrap();
+        verify_sp_fields(PacketType::Tc, &sp_header);
+    }
+
+    #[test]
+    fn test_tc_ctor_unseg() {
+        let sp_header = SpHeader::tc_unseg(0x42, 25, 0);
+        assert!(sp_header.is_some());
+        let sp_header = sp_header.unwrap();
+        verify_sp_fields(PacketType::Tc, &sp_header);
+    }
+
+    #[test]
+    fn test_tm_ctor() {
+        let sp_header = SpHeader::tm(0x42, SequenceFlags::Unsegmented, 25, 0);
+        assert!(sp_header.is_some());
+        let sp_header = sp_header.unwrap();
+        verify_sp_fields(PacketType::Tm, &sp_header);
+    }
+
+    #[test]
+    fn test_tm_ctor_unseg() {
+        let sp_header = SpHeader::tm_unseg(0x42, 25, 0);
+        assert!(sp_header.is_some());
+        let sp_header = sp_header.unwrap();
+        verify_sp_fields(PacketType::Tm, &sp_header);
+    }
+
+    fn verify_sp_fields(ptype: PacketType, sp_header: &SpHeader) {
+        assert_eq!(sp_header.ptype(), ptype);
+        assert_eq!(sp_header.sequence_flags(), SequenceFlags::Unsegmented);
+        assert_eq!(sp_header.apid(), 0x42);
+        assert_eq!(sp_header.seq_count(), 25);
+        assert_eq!(sp_header.data_len(), 0);
     }
 
     #[test]
     fn test_zc_sph() {
         use zerocopy::AsBytes;
 
-        let sp_header = SpHeader::tc(0x7FF, pow(2, 14) - 1, 0).expect("Error creating SP header");
+        let sp_header =
+            SpHeader::tc_unseg(0x7FF, pow(2, 14) - 1, 0).expect("Error creating SP header");
         assert_eq!(sp_header.ptype(), PacketType::Tc);
         assert_eq!(sp_header.apid(), 0x7FF);
         assert_eq!(sp_header.data_len(), 0);
diff --git a/src/tc.rs b/src/tc.rs
index a177ae8..f8de0aa 100644
--- a/src/tc.rs
+++ b/src/tc.rs
@@ -9,7 +9,7 @@
 //! use spacepackets::ecss::PusPacket;
 //!
 //! // Create a ping telecommand with no user application data
-//! let mut sph = SpHeader::tc(0x02, 0x34, 0).unwrap();
+//! let mut sph = SpHeader::tc_unseg(0x02, 0x34, 0).unwrap();
 //! let tc_header = PusTcSecondaryHeader::new_simple(17, 1);
 //! let pus_tc = PusTc::new(&mut sph, tc_header, None, true);
 //! println!("{:?}", pus_tc);
@@ -41,6 +41,7 @@ use crate::{
 };
 use core::mem::size_of;
 use delegate::delegate;
+#[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 use zerocopy::AsBytes;
 
@@ -66,7 +67,7 @@ pub const ACK_ALL: u8 = AckOpts::Acceptance as u8
     | AckOpts::Progress as u8
     | AckOpts::Completion as u8;
 
-pub trait PusTcSecondaryHeaderT {
+pub trait GenericPusTcSecondaryHeader {
     fn pus_version(&self) -> PusVersion;
     fn ack_flags(&self) -> u8;
     fn service(&self) -> u8;
@@ -76,7 +77,7 @@ pub trait PusTcSecondaryHeaderT {
 
 pub mod zc {
     use crate::ecss::{PusError, PusVersion};
-    use crate::tc::PusTcSecondaryHeaderT;
+    use crate::tc::GenericPusTcSecondaryHeader;
     use zerocopy::{AsBytes, FromBytes, NetworkEndian, Unaligned, U16};
 
     #[derive(FromBytes, AsBytes, Unaligned)]
@@ -103,7 +104,7 @@ pub mod zc {
         }
     }
 
-    impl PusTcSecondaryHeaderT for PusTcSecondaryHeader {
+    impl GenericPusTcSecondaryHeader for PusTcSecondaryHeader {
         fn pus_version(&self) -> PusVersion {
             PusVersion::try_from(self.version_ack >> 4 & 0b1111).unwrap_or(PusVersion::Invalid)
         }
@@ -136,7 +137,8 @@ pub mod zc {
     }
 }
 
-#[derive(PartialEq, Eq, Copy, Clone, Serialize, Deserialize, Debug)]
+#[derive(PartialEq, Eq, Copy, Clone, Debug)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct PusTcSecondaryHeader {
     pub service: u8,
     pub subservice: u8,
@@ -145,7 +147,7 @@ pub struct PusTcSecondaryHeader {
     pub version: PusVersion,
 }
 
-impl PusTcSecondaryHeaderT for PusTcSecondaryHeader {
+impl GenericPusTcSecondaryHeader for PusTcSecondaryHeader {
     fn pus_version(&self) -> PusVersion {
         self.version
     }
@@ -211,14 +213,15 @@ impl PusTcSecondaryHeader {
 /// [postcard](https://docs.rs/postcard/latest/postcard/).
 ///
 /// There is no spare bytes support yet.
-#[derive(PartialEq, Eq, Copy, Clone, Serialize, Deserialize, Debug)]
+#[derive(PartialEq, Eq, Copy, Clone, Debug)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct PusTc<'slice> {
     sp_header: SpHeader,
     pub sec_header: PusTcSecondaryHeader,
     /// If this is set to false, a manual call to [PusTc::calc_own_crc16] or
     /// [PusTc::update_packet_fields] is necessary for the serialized or cached CRC16 to be valid.
     pub calc_crc_on_serialization: bool,
-    #[serde(skip)]
+    #[cfg_attr(feature = "serde", serde(skip))]
     raw_data: Option<&'slice [u8]>,
     app_data: Option<&'slice [u8]>,
     crc16: Option<u16>,
@@ -260,7 +263,7 @@ impl<'slice> PusTc<'slice> {
     }
 
     /// Simplified version of the [PusTc::new] function which allows to only specify service and
-    /// subservice instead of the full PUS TC secondary header
+    /// subservice instead of the full PUS TC secondary header.
     pub fn new_simple(
         sph: &mut SpHeader,
         service: u8,
@@ -303,7 +306,7 @@ impl<'slice> PusTc<'slice> {
     /// used.
     /// If this was not done or the application data is set or changed after construction,
     /// this function needs to be called to ensure that the data length field of the CCSDS header
-    /// is set correctly
+    /// is set correctly.
     pub fn update_ccsds_data_len(&mut self) {
         self.sp_header.data_len =
             self.len_packed() as u16 - size_of::<crate::zc::SpHeader>() as u16 - 1;
@@ -323,7 +326,7 @@ impl<'slice> PusTc<'slice> {
         self.crc16 = Some(digest.finalize())
     }
 
-    /// This helper function calls both [PusTc.update_ccsds_data_len] and [PusTc.calc_own_crc16]
+    /// This helper function calls both [PusTc.update_ccsds_data_len] and [PusTc.calc_own_crc16].
     pub fn update_packet_fields(&mut self) {
         self.update_ccsds_data_len();
         self.calc_own_crc16();
@@ -401,7 +404,7 @@ impl<'slice> PusTc<'slice> {
     }
 
     /// Create a [PusTc] instance from a raw slice. On success, it returns a tuple containing
-    /// the instance and the found byte length of the packet
+    /// the instance and the found byte length of the packet.
     pub fn from_bytes(slice: &'slice [u8]) -> Result<(Self, usize), PusError> {
         let raw_data_len = slice.len();
         if raw_data_len < PUS_TC_MIN_LEN_WITHOUT_APP_DATA {
@@ -462,7 +465,7 @@ impl PusPacket for PusTc<'_> {
 }
 
 //noinspection RsTraitImplementation
-impl PusTcSecondaryHeaderT for PusTc<'_> {
+impl GenericPusTcSecondaryHeader for PusTc<'_> {
     delegate!(to self.sec_header {
         fn pus_version(&self) -> PusVersion;
         fn service(&self) -> u8;
@@ -472,29 +475,29 @@ impl PusTcSecondaryHeaderT for PusTc<'_> {
     });
 }
 
-#[cfg(test)]
+#[cfg(all(test, feature = "std"))]
 mod tests {
     use crate::ecss::PusVersion::PusC;
     use crate::ecss::{PusError, PusPacket};
     use crate::tc::ACK_ALL;
-    use crate::tc::{PusTc, PusTcSecondaryHeader, PusTcSecondaryHeaderT};
+    use crate::tc::{GenericPusTcSecondaryHeader, PusTc, PusTcSecondaryHeader};
     use crate::{ByteConversionError, SpHeader};
     use crate::{CcsdsPacket, SequenceFlags};
     use alloc::vec::Vec;
 
     fn base_ping_tc_full_ctor() -> PusTc<'static> {
-        let mut sph = SpHeader::tc(0x02, 0x34, 0).unwrap();
+        let mut sph = SpHeader::tc_unseg(0x02, 0x34, 0).unwrap();
         let tc_header = PusTcSecondaryHeader::new_simple(17, 1);
         PusTc::new(&mut sph, tc_header, None, true)
     }
 
     fn base_ping_tc_simple_ctor() -> PusTc<'static> {
-        let mut sph = SpHeader::tc(0x02, 0x34, 0).unwrap();
+        let mut sph = SpHeader::tc_unseg(0x02, 0x34, 0).unwrap();
         PusTc::new_simple(&mut sph, 17, 1, None, true)
     }
 
     fn base_ping_tc_simple_ctor_with_app_data(app_data: &'static [u8]) -> PusTc<'static> {
-        let mut sph = SpHeader::tc(0x02, 0x34, 0).unwrap();
+        let mut sph = SpHeader::tc_unseg(0x02, 0x34, 0).unwrap();
         PusTc::new_simple(&mut sph, 17, 1, Some(app_data), true)
     }
 
@@ -534,7 +537,7 @@ mod tests {
 
     #[test]
     fn test_update_func() {
-        let mut sph = SpHeader::tc(0x02, 0x34, 0).unwrap();
+        let mut sph = SpHeader::tc_unseg(0x02, 0x34, 0).unwrap();
         let mut tc = PusTc::new_simple(&mut sph, 17, 1, None, false);
         tc.calc_crc_on_serialization = false;
         assert_eq!(tc.data_len(), 0);
@@ -560,7 +563,6 @@ mod tests {
     }
 
     #[test]
-    #[cfg(feature = "alloc")]
     fn test_vec_ser_deser() {
         let pus_tc = base_ping_tc_simple_ctor();
         let mut test_vec = Vec::new();
@@ -625,7 +627,7 @@ mod tests {
     }
 
     #[test]
-    fn test_write_buf_too_msall() {
+    fn test_write_buf_too_small() {
         let pus_tc = base_ping_tc_simple_ctor();
         let mut test_buf = [0; 12];
         let res = pus_tc.write_to_bytes(test_buf.as_mut_slice());
@@ -698,7 +700,7 @@ mod tests {
         assert_eq!(tc.apid(), 0x02);
         assert_eq!(tc.ack_flags(), ACK_ALL);
         assert_eq!(tc.len_packed(), exp_full_len);
-        let mut comp_header = SpHeader::tc(0x02, 0x34, exp_full_len as u16 - 7).unwrap();
+        let mut comp_header = SpHeader::tc_unseg(0x02, 0x34, exp_full_len as u16 - 7).unwrap();
         comp_header.set_sec_header_flag();
         assert_eq!(tc.sp_header, comp_header);
     }
diff --git a/src/time.rs b/src/time.rs
index 3d70783..0ae8141 100644
--- a/src/time.rs
+++ b/src/time.rs
@@ -10,11 +10,15 @@ use crate::time::CcsdsTimeCodes::Cds;
 #[cfg(feature = "std")]
 use std::time::{SystemTime, SystemTimeError};
 
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
 pub const CDS_SHORT_LEN: usize = 7;
 pub const DAYS_CCSDS_TO_UNIX: i32 = -4383;
 pub const SECONDS_PER_DAY: u32 = 86400;
 
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum CcsdsTimeCodes {
     None = 0,
     CucCcsdsEpoch = 0b001,
@@ -23,7 +27,7 @@ pub enum CcsdsTimeCodes {
     Ccs = 0b101,
 }
 
-const CDS_SHORT_P_FIELD: u8 = (CcsdsTimeCodes::Cds as u8) << 4;
+const CDS_SHORT_P_FIELD: u8 = (Cds as u8) << 4;
 
 impl TryFrom<u8> for CcsdsTimeCodes {
     type Error = ();
@@ -41,6 +45,7 @@ impl TryFrom<u8> for CcsdsTimeCodes {
 }
 
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum TimestampError {
     /// Contains tuple where first value is the expected time code and the second
     /// value is the found raw value
@@ -83,7 +88,7 @@ pub trait TimeReader {
         Self: Sized;
 }
 
-/// Trait for generic CCSDS time providers
+/// Trait for generic CCSDS time providers.
 pub trait CcsdsTimeProvider {
     fn len_as_bytes(&self) -> usize;
 
@@ -112,12 +117,12 @@ pub trait CcsdsTimeProvider {
 /// timestamp_now.write_to_bytes(&mut raw_stamp).unwrap();
 /// assert_eq!((raw_stamp[0] >> 4) & 0b111, Cds as u8);
 /// ```
-#[derive(Debug, Copy, Clone, Default)]
+#[derive(Debug, Copy, Clone, Default, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct CdsShortTimeProvider {
     ccsds_days: u16,
     ms_of_day: u32,
     unix_seconds: i64,
-    date_time: Option<DateTime<Utc>>,
 }
 
 impl CdsShortTimeProvider {
@@ -126,7 +131,6 @@ impl CdsShortTimeProvider {
             ccsds_days,
             ms_of_day,
             unix_seconds: 0,
-            date_time: None,
         };
         let unix_days_seconds =
             ccsds_to_unix_days(ccsds_days as i32) as i64 * SECONDS_PER_DAY as i64;
@@ -146,7 +150,6 @@ impl CdsShortTimeProvider {
                 as u16,
             ms_of_day: ms_of_day as u32,
             unix_seconds: 0,
-            date_time: None,
         };
         Ok(provider.setup(unix_days_seconds as i64, ms_of_day))
     }
@@ -165,7 +168,6 @@ impl CdsShortTimeProvider {
 
     fn setup(mut self, unix_days_seconds: i64, ms_of_day: u64) -> Self {
         self.calc_unix_seconds(unix_days_seconds, ms_of_day);
-        self.calc_date_time((ms_of_day % 1000) as u32);
         self
     }
 
@@ -193,14 +195,13 @@ impl CdsShortTimeProvider {
         }
     }
 
-    fn calc_date_time(&mut self, ms_since_last_second: u32) {
+    fn calc_date_time(&self, ms_since_last_second: u32) -> Option<DateTime<Utc>> {
         assert!(ms_since_last_second < 1000, "Invalid MS since last second");
         let ns_since_last_sec = ms_since_last_second * 1e6 as u32;
         if let LocalResult::Single(val) = Utc.timestamp_opt(self.unix_seconds, ns_since_last_sec) {
-            self.date_time = Some(val);
-        } else {
-            self.date_time = None;
+            return Some(val);
         }
+        None
     }
 }
 
@@ -222,7 +223,7 @@ impl CcsdsTimeProvider for CdsShortTimeProvider {
     }
 
     fn date_time(&self) -> Option<DateTime<Utc>> {
-        self.date_time
+        self.calc_date_time((self.ms_of_day % 1000) as u32)
     }
 }
 
@@ -267,13 +268,15 @@ impl TimeReader for CdsShortTimeProvider {
     }
 }
 
-#[cfg(test)]
+#[cfg(all(test, feature = "std"))]
 mod tests {
     use super::*;
     use crate::time::TimestampError::{InvalidTimeCode, OtherPacketError};
     use crate::ByteConversionError::{FromSliceTooSmall, ToSliceTooSmall};
     use alloc::format;
     use chrono::{Datelike, Timelike};
+    #[cfg(feature = "serde")]
+    use postcard::{from_bytes, to_allocvec};
 
     #[test]
     fn test_creation() {
@@ -281,7 +284,6 @@ mod tests {
         assert_eq!(ccsds_to_unix_days(0), DAYS_CCSDS_TO_UNIX);
     }
 
-    #[cfg(feature = "std")]
     #[test]
     fn test_get_current_time() {
         let sec_floats = seconds_since_epoch();
@@ -429,7 +431,6 @@ mod tests {
         assert_eq!(read_stamp.ms_of_day, u32::MAX - 1);
     }
 
-    #[cfg(feature = "std")]
     #[test]
     fn test_time_now() {
         let timestamp_now = CdsShortTimeProvider::from_now().unwrap();
@@ -455,7 +456,17 @@ mod tests {
         generic_dt_property_equality_check(dt.minute(), compare_stamp.minute(), 0, 59);
     }
 
-    #[cfg(feature = "std")]
+    #[test]
+    #[cfg(feature = "serde")]
+    fn test_serialization() {
+        let stamp_now = CdsShortTimeProvider::from_now().expect("Error retrieving time");
+        let val = to_allocvec(&stamp_now).expect("Serializing timestamp failed");
+        assert!(val.len() > 0);
+        let stamp_deser: CdsShortTimeProvider =
+            from_bytes(&val).expect("Stamp deserialization failed");
+        assert_eq!(stamp_deser, stamp_now);
+    }
+
     fn generic_dt_property_equality_check(first: u32, second: u32, start: u32, end: u32) {
         if second < first {
             assert_eq!(second, start);
diff --git a/src/tm.rs b/src/tm.rs
index da40589..220094b 100644
--- a/src/tm.rs
+++ b/src/tm.rs
@@ -9,6 +9,7 @@ use crate::{
     CCSDS_HEADER_LEN,
 };
 use core::mem::size_of;
+#[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 use zerocopy::AsBytes;
 
@@ -21,7 +22,7 @@ pub const PUC_TM_MIN_SEC_HEADER_LEN: usize = 7;
 pub const PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA: usize =
     CCSDS_HEADER_LEN + PUC_TM_MIN_SEC_HEADER_LEN + size_of::<CrcType>();
 
-pub trait PusTmSecondaryHeaderT {
+pub trait GenericPusTmSecondaryHeader {
     fn pus_version(&self) -> PusVersion;
     fn sc_time_ref_status(&self) -> u8;
     fn service(&self) -> u8;
@@ -31,6 +32,7 @@ pub trait PusTmSecondaryHeaderT {
 }
 
 pub mod zc {
+    use super::GenericPusTmSecondaryHeader;
     use crate::ecss::{PusError, PusVersion};
     use zerocopy::{AsBytes, FromBytes, NetworkEndian, Unaligned, U16};
 
@@ -76,7 +78,7 @@ pub mod zc {
         }
     }
 
-    impl super::PusTmSecondaryHeaderT for PusTmSecHeaderWithoutTimestamp {
+    impl GenericPusTmSecondaryHeader for PusTmSecHeaderWithoutTimestamp {
         fn pus_version(&self) -> PusVersion {
             PusVersion::try_from(self.pus_version_and_sc_time_ref_status >> 4 & 0b1111)
                 .unwrap_or(PusVersion::Invalid)
@@ -104,7 +106,8 @@ pub mod zc {
     }
 }
 
-#[derive(PartialEq, Eq, Serialize, Deserialize, Copy, Clone, Debug)]
+#[derive(PartialEq, Eq, Copy, Clone, Debug)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct PusTmSecondaryHeader<'slice> {
     pus_version: PusVersion,
     pub sc_time_ref_status: u8,
@@ -147,7 +150,7 @@ impl<'slice> PusTmSecondaryHeader<'slice> {
     }
 }
 
-impl PusTmSecondaryHeaderT for PusTmSecondaryHeader<'_> {
+impl GenericPusTmSecondaryHeader for PusTmSecondaryHeader<'_> {
     fn pus_version(&self) -> PusVersion {
         self.pus_version
     }
@@ -198,14 +201,15 @@ impl<'slice> TryFrom<zc::PusTmSecHeader<'slice>> for PusTmSecondaryHeader<'slice
 /// [postcard](https://docs.rs/postcard/latest/postcard/).
 ///
 /// There is no spare bytes support yet.
-#[derive(PartialEq, Eq, Serialize, Deserialize, Debug, Copy, Clone)]
+#[derive(PartialEq, Eq, Debug, Copy, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct PusTm<'slice> {
     pub sp_header: SpHeader,
     pub sec_header: PusTmSecondaryHeader<'slice>,
     /// If this is set to false, a manual call to [PusTm::calc_own_crc16] or
     /// [PusTm::update_packet_fields] is necessary for the serialized or cached CRC16 to be valid.
     pub calc_crc_on_serialization: bool,
-    #[serde(skip)]
+    #[cfg_attr(feature = "serde", serde(skip))]
     raw_data: Option<&'slice [u8]>,
     source_data: Option<&'slice [u8]>,
     crc16: Option<u16>,
@@ -452,7 +456,7 @@ impl PusPacket for PusTm<'_> {
 }
 
 //noinspection RsTraitImplementation
-impl PusTmSecondaryHeaderT for PusTm<'_> {
+impl GenericPusTmSecondaryHeader for PusTm<'_> {
     delegate!(to self.sec_header {
         fn pus_version(&self) -> PusVersion;
         fn service(&self) -> u8;
@@ -470,13 +474,13 @@ mod tests {
     use crate::SpHeader;
 
     fn base_ping_reply_full_ctor(time_stamp: &[u8]) -> PusTm {
-        let mut sph = SpHeader::tm(0x123, 0x234, 0).unwrap();
+        let mut sph = SpHeader::tm_unseg(0x123, 0x234, 0).unwrap();
         let tc_header = PusTmSecondaryHeader::new_simple(17, 2, &time_stamp);
         PusTm::new(&mut sph, tc_header, None, true)
     }
 
     fn base_hk_reply<'a>(time_stamp: &'a [u8], src_data: &'a [u8]) -> PusTm<'a> {
-        let mut sph = SpHeader::tm(0x123, 0x234, 0).unwrap();
+        let mut sph = SpHeader::tm_unseg(0x123, 0x234, 0).unwrap();
         let tc_header = PusTmSecondaryHeader::new_simple(3, 5, &time_stamp);
         PusTm::new(&mut sph, tc_header, Some(src_data), true)
     }
@@ -548,7 +552,7 @@ mod tests {
 
     #[test]
     fn test_manual_field_update() {
-        let mut sph = SpHeader::tm(0x123, 0x234, 0).unwrap();
+        let mut sph = SpHeader::tm_unseg(0x123, 0x234, 0).unwrap();
         let tc_header = PusTmSecondaryHeader::new_simple(17, 2, dummy_time_stamp());
         let mut tm = PusTm::new(&mut sph, tc_header, None, false);
         tm.calc_crc_on_serialization = false;