UART Communication Test Suite

Overview

The uart_multi_node_comprehensive_test.cpp tests TMC51x0 UART single-wire communication with 1 or more drivers. It exercises the full communication stack – from raw register access through motor control – over UART instead of SPI.

Purpose

This test suite validates:

  • ESP32 UART interface initialization and baud rate sync with the TMC5160
  • Register read/write communication (IOIN, GCONF)
  • Node address configuration (NODECONF register)
  • Send delay configuration for multi-node systems
  • Full motor control (ramp, enable, positioning) over UART

Test Categories

1. Basic UART Communication

Initializes the driver, reads IOIN (chip version) and GCONF to verify the UART link, CRC, and frame structure all work.

What it proves: The Esp32UART class correctly implements UartSend() / UartReceive(), the TMC5160 auto-detects the baud rate from the sync frame, and CRC8 checksums are valid in both directions.

2. Node Address Configuration

Writes a new address (e.g. 42) via ConfigureUartNodeAddress(), then reads IOIN on that address to confirm the chip responds. Restores address 0 afterward.

What it proves: The NODECONF register write works, and the driver correctly tracks the address in software so subsequent reads use the new address.

3. Send Delay Configuration

Iterates through SENDDELAY values (0, 1, 2, 4, 8) and reads IOIN after each to verify communication still works. SENDDELAY controls how many bit-times the TMC5160 waits before replying.

What it proves: The receive timeout in Esp32UART::UartReceive() handles varying reply delays correctly. For multi-node systems, SENDDELAY >= 2 is required.

4. Motor Control via UART

Initializes ramp parameters, enables the motor, commands a 45-degree move, and polls IsTargetReached() until the motor arrives. This proves the full driver API works over UART.

What it proves: All driver subsystems (motorControl, rampControl) function correctly over UART, not just raw register access.

Hardware Configuration

Single-Driver Setup (default: TEST_NODE_COUNT = 1) 

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ESP32                TMC5160
GPIO 17 (TX) ------> SWN (pin 26 / DIAG0_SWN)
GPIO 16 (RX) <------ SWP (pin 27 / DIAG1_SWP)
GPIO 11      ------> DRV_ENN (enable)
GND          ------> SD_MODE (pin 21) -- LOW for UART mode
GND          ------> SPI_MODE (pin 22) -- LOW for UART mode

Multi-Driver UART Bus

All chips share the same TX/RX lines. NAI/NAO pins form an addressing chain:

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ESP32          Chip 1                Chip 2
TX  ---------- SWN ------------------- SWN
RX  ---------- SWP ------------------- SWP
GND ---------- NAI (SDI_CFG1)
               NAO (SDO_CFG0) -------- NAI (SDI_CFG1)

Pin Configuration

Default pins (edit in the source file):

Signal GPIO Description
UART TX 17 ESP32 TX -> TMC5160 SWN
UART RX 16 ESP32 RX <- TMC5160 SWP
EN 11 Motor enable (active LOW)
SD_MODE GND Must be LOW for UART mode
SPI_MODE GND Must be LOW for UART mode

Test Configuration

Adjust these constants in the source file:

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static constexpr uint8_t TEST_NODE_COUNT = 1;   // Number of TMC nodes on the bus
static constexpr uart_port_t UART_PORT = UART_NUM_1;
static constexpr uint32_t UART_BAUD = 115200;   // TMC5160 auto-detects
static constexpr int UART_TX_PIN = 17;
static constexpr int UART_RX_PIN = 16;
static constexpr int EN_PIN      = 11;

Test sections can be individually enabled/disabled:

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static constexpr bool ENABLE_BASIC_COMM_TESTS = true;
static constexpr bool ENABLE_NODE_ADDRESS_TESTS = true;
static constexpr bool ENABLE_SEND_DELAY_TESTS = true;
static constexpr bool ENABLE_MOTOR_CONTROL_TESTS = true;

Code Structure

Esp32UART Communication Interface

Defined in test_config/esp32_tmc51x0_bus.hpp. Inherits from tmc51x0::UartCommInterface<Esp32UART> (CRTP) and implements:

Method Description
Initialize() Configures ESP-IDF UART driver, sets pins, flushes stale data
UartSend() Writes frame bytes, waits for TX FIFO drain, flushes echo
UartReceive() Reads reply bytes with 100 ms timeout
GpioSet() / GpioRead() Same pin abstraction as Esp32SPI
DelayMs() / DelayUs() FreeRTOS and ROM delays

Test Flow

  1. create_uart_drivers() – Creates Esp32UART + N driver instances
  2. Each test initializes the driver with DriverConfig from the test rig config
  3. Tests exercise register access, node addressing, or motor control
  4. Results reported via the test framework

Expected Behavior

Typical Output (single node) 

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I UART_MultiNode_Test: ==============================================================
I UART_MultiNode_Test:   ESP32 TMC51x0 UART Communication Test Suite
I UART_MultiNode_Test: ==============================================================
I UART_MultiNode_Test: Node count: 1 | UART port: 1 | Baud: 115200 | TX=17 RX=16

I UART_MultiNode_Test: Driver 0: Initialized successfully
I UART_MultiNode_Test: Driver 0: GCONF = 0x00000004
I UART_MultiNode_Test: Driver 0: IOIN = 0x30XXXXXX (chip version: 0x30)
I UART_MultiNode_Test: [PASS] Basic UART Communication

I UART_MultiNode_Test: Node address updated to 42 (send delay: 2)
I UART_MultiNode_Test: Successfully read IOIN on address 42
I UART_MultiNode_Test: [PASS] Node Address Configuration

I UART_MultiNode_Test: SENDDELAY=0: read OK
I UART_MultiNode_Test: SENDDELAY=2: read OK
I UART_MultiNode_Test: SENDDELAY=8: read OK
I UART_MultiNode_Test: [PASS] Send Delay Configuration

I UART_MultiNode_Test: Driver 0: Moving to 45.0 degrees...
I UART_MultiNode_Test: All 1 driver(s) reached target position
I UART_MultiNode_Test: [PASS] Motor Control via UART

Troubleshooting

No Response from TMC5160

Check Fix
Mode pins SD_MODE and SPI_MODE must both be LOW (GND)
TX/RX wiring TX -> SWN (pin 26), RX <- SWP (pin 27)
Baud rate Try 9600 or 57600 if 115200 doesn’t work
Power VM supply must be present for UART to work
UART port Avoid UART_NUM_0 (console); use UART_NUM_1 or UART_NUM_2

CRC Errors or Garbled Data

  • Check for loose connections on TX/RX
  • Ensure no other device is driving the UART lines
  • Reduce baud rate (TMC5160 minimum is ~9000 baud at 20 MHz clock)

Motor Doesn’t Move

  • Verify EN pin is wired and motor supply (VM) is present
  • Check IRUN/IHOLD settings match your sense resistors
  • Read DRV_STATUS for fault flags (drv_err, uv_cp, ot)
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