diff --git a/.github/workflows/build.yaml b/.github/workflows/build.yaml
index c049ced..3c2f32d 100644
--- a/.github/workflows/build.yaml
+++ b/.github/workflows/build.yaml
@@ -1,5 +1,9 @@
 name: Build Firmware
-on: [push, pull_request]
+on:
+  push:
+    branches:
+      - main
+  pull_request:
 
 jobs:
   build:
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 40418c3..78901bc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,9 @@
+### 0.4.0 (2024/01/04)
+
+* Provide EEPROM commands.
+* Provide a method for the Teensy to read it's own USB Serial Number back to
+  the device through the USB interface.
+
 ### 0.3.0 (2023/11/06)
 
 * Increase the maximum analog pulse duration to 3 minutes.
diff --git a/platformio.ini b/platformio.ini
index 1862407..acede48 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -13,6 +13,7 @@ platform = teensy
 board = teensy31
 framework = arduino
 board_build.f_cpu = 96000000L
+upload_protocol = teensy-cli
 lib_deps =
     https://github.com/nox771/i2c_t3.git
 build_flags =
diff --git a/src/commandconstants.hpp b/src/commandconstants.hpp
index eb61733..77b1f79 100644
--- a/src/commandconstants.hpp
+++ b/src/commandconstants.hpp
@@ -6,6 +6,7 @@ int info_func(CommandRouter *cmd, int argc, const char **argv);
 int reboot_func(CommandRouter *cmd, int argc, const char **argv);
 int version_func(CommandRouter *cmd, int argc, const char **argv);
 int mcu_func(CommandRouter *cmd, int argc, const char **argv);
+int serialnumber_func(CommandRouter *cmd, int argc, const char **argv);
 int command_license_func(CommandRouter *cmd, int argc, const char **argv);
 
 // Digital GPIO
@@ -58,12 +59,21 @@ int register_read_uint16(CommandRouter *cmd, int argc, const char **argv);
 int register_write_uint16(CommandRouter *cmd, int argc, const char **argv);
 int register_read_uint32(CommandRouter *cmd, int argc, const char **argv);
 int register_write_uint32(CommandRouter *cmd, int argc, const char **argv);
+
+int eeprom_length(CommandRouter *cmd, int argc, const char **argv);
+int eeprom_read_uint8(CommandRouter *cmd, int argc, const char **argv);
+int eeprom_write_uint8(CommandRouter *cmd, int argc, const char **argv);
+int eeprom_update_uint8(CommandRouter *cmd, int argc, const char **argv);
+int eeprom_read_string(CommandRouter *cmd, int argc, const char **argv);
+int eeprom_write_string(CommandRouter *cmd, int argc, const char **argv);
+
 // Syntax is: {short command, description, syntax}
 const command_item_t command_list[] = {
     {"?", "Display help info", "?", command_help_func},
     {"info", "Displays information about this TeensyToAny device", "about", info_func},
     {"reboot", "Runs setup routine again, for this device.", "reboot", reboot_func},
     {"mcu", "Displays information about the microcontroller board.", "mcu", mcu_func},
+    {"serialnumber", "Displays the serial number of the board.", "serialnumber", serialnumber_func},
     {"license",
      "Display the license information for the source code running on the "
      "teensy",
@@ -162,5 +172,17 @@ const command_item_t command_list[] = {
      "register_read_uint32 address", register_read_uint32},
     {"register_write_uint32", "Write to an arbitrary hardware register.",
      "register_write_uint32 address data", register_write_uint32},
+    {"eeprom_length", "Return the size of the of the EEPROM in bytes.",
+     "eeprom_length", eeprom_length},
+    {"eeprom_read_uint8", "Read data from a given EEPROM address.",
+     "eeprom_read_uint8 address", eeprom_read_uint8},
+    {"eeprom_write_uint8", "Write to an EEPROM address.",
+     "eeprom_write_uint8 address data", eeprom_write_uint8},
+    {"eeprom_update_uint8", "Write to an EEPROM address if the value has changed.",
+     "eeprom_update_uint8 address data", eeprom_update_uint8},
+    {"eeprom_read_string", "Read data from a given EEPROM address.",
+     "eeprom_read_string address", eeprom_read_string},
+    {"eeprom_write_string", "Write to an EEPROM address.",
+     "eeprom_write_string address data", eeprom_write_string},
     {nullptr, nullptr, nullptr, nullptr},
 };
diff --git a/src/main.cpp b/src/main.cpp
index 1c8f6eb..4cc0441 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -4,6 +4,8 @@
 #include <Arduino.h>
 #include <SPI.h>
 #include <errno.h>
+#include <usb_names.h>
+#include <EEPROM.h>
 
 // TODO: this isn't exactly correct since this main file won't get
 // regenerated if it wasn't touched.
@@ -73,6 +75,23 @@ int version_func(CommandRouter *cmd, int argc, const char **argv) {
   return 0;
 }
 
+int serialnumber_func(CommandRouter *cmd, int argc, const char **argv) {
+  (void)argc;
+  (void)argv;
+  uint8_t i;
+  // https://github.com/PaulStoffregen/cores/pull/722
+#pragma GCC diagnostic push
+  // https://gcc.gnu.org/onlinedocs/gcc/Diagnostic-Pragmas.html
+#pragma GCC diagnostic ignored "-Warray-bounds"
+  for (i=0; i < (usb_string_serial_number.bLength - 2) / sizeof(uint16_t); i++) {
+    cmd->buffer[i] = (char)usb_string_serial_number.wString[i];
+  }
+#pragma GCC diagnostic pop
+  cmd->buffer[i] = '\0';
+  return 0;
+}
+
+
 int mcu_func(CommandRouter *cmd, int argc, const char **argv) {
   (void)argc;
   (void)argv;
@@ -859,6 +878,157 @@ int register_read_uint32(CommandRouter *cmd, int argc, const char **argv) {
   return 0;
 }
 
+int eeprom_length(CommandRouter *cmd, int argc, const char **argv) {
+  if (argc != 1) {
+    return EINVAL;
+  }
+
+  uint16_t length = EEPROM.length();
+
+  snprintf(cmd->buffer, cmd->buffer_size, "0x%04X", length);
+
+  return 0;
+}
+
+int eeprom_read_uint8(CommandRouter *cmd, int argc, const char **argv) {
+  if (argc != 2) {
+    return EINVAL;
+  }
+  int index;
+  uint8_t data;
+
+  index = strtol(argv[1], nullptr, 0);
+  if (index > EEPROM.length()) {
+    return EINVAL;
+  }
+
+  data = EEPROM.read(index);
+
+  snprintf(cmd->buffer, cmd->buffer_size, "0x%02X", data);
+
+  return 0;
+}
+
+int eeprom_write_uint8(CommandRouter *cmd, int argc, const char **argv) {
+  if (argc != 3) {
+    return EINVAL;
+  }
+  int index;
+  uint8_t data;
+
+  index = strtol(argv[1], nullptr, 0);
+  data = strtol(argv[2], nullptr, 0);
+  if (index > EEPROM.length()) {
+    return EINVAL;
+  }
+
+  EEPROM.write(index, data);
+
+  return 0;
+}
+
+int eeprom_update_uint8(CommandRouter *cmd, int argc, const char **argv) {
+  if (argc != 3) {
+    return EINVAL;
+  }
+  int index;
+  uint8_t data;
+
+  index = strtol(argv[1], nullptr, 0);
+  data = strtol(argv[2], nullptr, 0);
+  if (index > EEPROM.length()) {
+    return EINVAL;
+  }
+
+  /*
+    The function EEPROM.update(address, val) is equivalent to the following:
+
+    if( EEPROM.read(address) != val ){
+      EEPROM.write(address, val);
+    }
+  */
+  EEPROM.update(index, data);
+
+  return 0;
+}
+
+int eeprom_read_string(CommandRouter *cmd, int argc, const char **argv) {
+  if (argc < 2 || argc > 3) {
+    return EINVAL;
+  }
+  int index, i;
+  int n_read;
+  char data;
+
+  index = strtol(argv[1], nullptr, 0);
+  if (index > EEPROM.length()) {
+    return EINVAL;
+  }
+  if (argc >= 3) {
+    n_read = strtol(argv[2], nullptr, 0);
+  } else {
+    n_read = EEPROM.length() - index;
+  }
+
+  if (index + n_read > EEPROM.length()) {
+    return EINVAL;
+  }
+
+  for(i=0; i < n_read; i++, index++){
+    data = (char) EEPROM.read(index);
+
+    if (data == '\0') {
+      break;
+    }
+
+    cmd->buffer[i] = data;
+  }
+  // Terminate, always, even if we "got to the end of EEPROM's length
+  cmd->buffer[i] = '\0';
+
+  return 0;
+}
+
+int eeprom_write_string(CommandRouter *cmd, int argc, const char **argv) {
+  if (argc < 3) {
+    return EINVAL;
+  }
+  int index, i;
+  int data_length;
+  const char* data;
+
+  index = strtol(argv[1], nullptr, 0);
+  if (index > EEPROM.length()) {
+    return EINVAL;
+  }
+
+  // We compute the length of the string "joined" by spaces
+  data_length = argc - 3;
+  for (i=2; i < argc; i++) {
+    data = argv[2];
+    data_length += strlen(data);
+  }
+
+  if (index + data_length >= EEPROM.length()) {
+    return EINVAL;
+  }
+
+  for (int j=2; j < argc; j++) {
+    data = argv[j];
+    if (j != 2) {
+      EEPROM.update(index, ' ');
+      ++index;
+    }
+    for(i=0; data[i] != '\0'; i++, index++){
+      EEPROM.update(index, data[i]);
+    }
+  }
+  EEPROM.update(index, '\0');
+
+  return 0;
+}
+
+
 
 void loop() {
   // TODO: remove this check on if Serial is available.
diff --git a/versioneer.py b/versioneer.py
index 8b5749e..8ff1e54 100644
--- a/versioneer.py
+++ b/versioneer.py
@@ -2,8 +2,8 @@
 
 revision = subprocess.check_output(["git", "describe", "--tags", "--dirty"]).strip()
 revision = revision.decode()
-revision = revision.replace('-dirty', '+dirty', 1)
-revision = revision.replace('-', '.post', 1)
+revision = revision.replace('-dirty', '.dirty', 1)
+revision = revision.replace('-', '.dev', 1)
 revision = revision.replace('-g', '+g', 1)
 
 print('-DGIT_DESCRIBE=\'"%s"\'' % revision)