PIC18 UART Driver

[AndrewWang001]

Initial Integration Test

Added

• pic18f26k83/uart.c
• include/uart.h
  (from ltt 2024 code)

Testing

1. Wiring

• Flash: Computer -> Snap -> LTT Board (MCLR etc)
• Power: 12V & Ground -> Power Supply
• TTL to USB Serial Converter (datasheet: https://www.ftdichip.com/Support/Documents/DataSheets/Cables/DS_[TTL-232R](https://www.ftdichip.com/Support/Documents/DataSheets/Cables/DS_TTL-232R_CABLES.pdf)_CABLES.pdf)
  • PIC18 GND -> USB-Serial GND (black)
  • PIC18 CTS -> USB-Serial CTS# (brown)
  • PIC18 RX -> USB-Serial RXD (yellow)
  • PIC18 TX -> USB-Serial TXD (orange)
  • PIC18 RTS -> USB-Serial RTS# (green)

2. Software

• switched to ltt repo to test uart
• used ltt's main as is, except
  • commented out all CAN/radio logic to remove console spam:

    // radio current checks
    // can_msg_t msg;
    // …

  • Inserted in loop:

    uint8_t test[] = "Hello World ";
    uart_transmit_buffer(test, sizeof(test) - 1);

• Build and Flash

3. Run

• Open PuTTY on COM port for FTDI cable (idk mac)
• 115200 baud rate
• should see text Hello World Hello World Hello World … printing every 500ms

[AndrewWang001]

Customization + Testing

UART driver tested on LTT hardware and verified working.

Steps taken:

• Switched to LTT codebase (uart.h, uart.c, and main.c)

• Replaced uart.h with the new version and inlined common.h to define w_status_t (since LTT didn’t include it)

• Replaced uart.c with the new version and re-added PPS pin configuration (was previously removed for external usage)

• Modified main.c to use the updated initialization call and uart sending:

  uart_init(115200, 48000000UL, true);

  const char *test = "Hello World V2.1 ";
  for (uint8_t i = 0; test[i] != '\0'; i++) {
     uart_transmit_byte(test[i]);
   }
  

• Modified main.c by deleting all the code irrelevant for UART (view test branch linked below)

• Flashed firmware and confirmed proper UART output in PuTTY at 115200 baud with flow control enabled

Correct output of "Hello World " repeating every 500ms — also noticed the weird garbage characters from early UART startup are now gone.

Tested with different baud rates as well (4800, 9600, 115200, etc)

🔗 Test branch (LTT repo):
https://github.com/waterloo-rocketry/cansw_telemetry_rfd/tree/UART_ltt_test