Part Number: TM4C129DNCPDT
Hello Tiva E2E Community,
I am having a consistent issue with UART communication on a custom TM4C129DNCPDT board. The UART works perfectly when connecting directly at 3.3V TTL levels, but communication fails only when the data signal passes through an SP3232EEN (RS-232 Transceiver IC).I have performed specific debugging tests (a visualization of all 5 tests is attached below) and summarized the results. I am confident the firmware (baud rate, PA6/PA7 pin config for UART2) is correct.
System Details:Controller: TM4C129DNCPDT
UART: UART2 (PA6=RX, PA7=TX)
Processor: SAMA5D36
Interface: SP3232EEN RS-232 Transceiver
Test Results (refer to attached diagram):
1. FULL SYSTEM (FAILED): Connecting the TM4C (via SP3232) to the SAMA5D (via SP3232) with jumper wires does not work.
2. DIRECT TTL (WORKS): Connecting TM4C UART2 directly to SAMA5D UART0 (bypassing all transceivers) works.
3. TM4C LOOPBACK (WORKS): Shorting PA7 to PA6 directly on the TM4C board (no transceiver) works.
4. SP3232EEN LOOPBACK (FAILED): Loopback test on the TM4C board after the signal passes through the SP3232EEN fails.
5. SAMA5D TEST (WORKS): I tested SAMA5D-to-SAMA5D communication back-to-back using the exact same SP3232EEN hardware from both boards. This configuration works, proving the transceivers and the wiring between them are functional.
Based on these tests, we have concluded the communication issue lies specifically within the level-shifting and signal drive stages involving the SP3232EEN transceivers.
We are looking for guidance on what to investigate next. Any insights from the TI community would be greatly appreciated. We have attached a block diagram illustrating the specific signal flow.Thank you for your support.
