General • Unable to see the output of I2C example program

Code:

/* * Copyright (c) 2021 Valentin Milea <valentin.milea@gmail.com> * Copyright (c) 2023 Raspberry Pi (Trading) Ltd. * * SPDX-License-Identifier: BSD-3-Clause */#include <hardware/i2c.h>#include <pico/i2c_slave.h>#include <pico/stdlib.h>#include <stdio.h>#include <string.h>static const uint I2C_SLAVE_ADDRESS = 0x17;static const uint I2C_BAUDRATE = 100000; // 100 kHz#ifdef i2c_default// For this example, we run both the master and slave from the same board.// You'll need to wire pin GP4 to GP6 (SDA), and pin GP5 to GP7 (SCL).static const uint I2C_SLAVE_SDA_PIN = PICO_DEFAULT_I2C_SDA_PIN; // 4static const uint I2C_SLAVE_SCL_PIN = PICO_DEFAULT_I2C_SCL_PIN; // 5static const uint I2C_MASTER_SDA_PIN = 6;static const uint I2C_MASTER_SCL_PIN = 7;// The slave implements a 256 byte memory. To write a series of bytes, the master first// writes the memory address, followed by the data. The address is automatically incremented// for each byte transferred, looping back to 0 upon reaching the end. Reading is done// sequentially from the current memory address.static struct{    uint8_t mem[256];    uint8_t mem_address;    bool mem_address_written;} context;// Our handler is called from the I2C ISR, so it must complete quickly. Blocking calls /// printing to stdio may interfere with interrupt handling.static void i2c_slave_handler(i2c_inst_t *i2c, i2c_slave_event_t event) {    switch (event) {    case I2C_SLAVE_RECEIVE: // master has written some data        if (!context.mem_address_written) {            // writes always start with the memory address            context.mem_address = i2c_read_byte_raw(i2c);            context.mem_address_written = true;        } else {            // save into memory            context.mem[context.mem_address] = i2c_read_byte_raw(i2c);            context.mem_address++;        }        break;    case I2C_SLAVE_REQUEST: // master is requesting data        // load from memory        i2c_write_byte_raw(i2c, context.mem[context.mem_address]);        context.mem_address++;        break;    case I2C_SLAVE_FINISH: // master has signalled Stop / Restart        context.mem_address_written = false;        break;    default:        break;    }}static void setup_slave() {    gpio_init(I2C_SLAVE_SDA_PIN);    gpio_set_function(I2C_SLAVE_SDA_PIN, GPIO_FUNC_I2C);    gpio_pull_up(I2C_SLAVE_SDA_PIN);    gpio_init(I2C_SLAVE_SCL_PIN);    gpio_set_function(I2C_SLAVE_SCL_PIN, GPIO_FUNC_I2C);    gpio_pull_up(I2C_SLAVE_SCL_PIN);    i2c_init(i2c0, I2C_BAUDRATE);    // configure I2C0 for slave mode    i2c_slave_init(i2c0, I2C_SLAVE_ADDRESS, &i2c_slave_handler);}static void run_master() {    gpio_init(I2C_MASTER_SDA_PIN);    gpio_set_function(I2C_MASTER_SDA_PIN, GPIO_FUNC_I2C);    // pull-ups are already active on slave side, this is just a fail-safe in case the wiring is faulty    gpio_pull_up(I2C_MASTER_SDA_PIN);    gpio_init(I2C_MASTER_SCL_PIN);    gpio_set_function(I2C_MASTER_SCL_PIN, GPIO_FUNC_I2C);    gpio_pull_up(I2C_MASTER_SCL_PIN);    i2c_init(i2c1, I2C_BAUDRATE);    for (uint8_t mem_address = 0;; mem_address = (mem_address + 32) % 256) {        char msg[32];        snprintf(msg, sizeof(msg), "Hello, I2C slave! - 0x%02X", mem_address);        uint8_t msg_len = strlen(msg);        uint8_t buf[32];        buf[0] = mem_address;        memcpy(buf + 1, msg, msg_len);        // write message at mem_address        printf("Write at 0x%02X: '%s'\n", mem_address, msg);        int count = i2c_write_blocking(i2c1, I2C_SLAVE_ADDRESS, buf, 1 + msg_len, false);        if (count < 0) {            puts("Couldn't write to slave, please check your wiring!");            return;        }        hard_assert(count == 1 + msg_len);        // seek to mem_address        count = i2c_write_blocking(i2c1, I2C_SLAVE_ADDRESS, buf, 1, true);        hard_assert(count == 1);        // partial read        uint8_t split = 5;        count = i2c_read_blocking(i2c1, I2C_SLAVE_ADDRESS, buf, split, true);        hard_assert(count == split);        buf[count] = '\0';        printf("Read  at 0x%02X: '%s'\n", mem_address, buf);        hard_assert(memcmp(buf, msg, split) == 0);        // read the remaining bytes, continuing from last address        count = i2c_read_blocking(i2c1, I2C_SLAVE_ADDRESS, buf, msg_len - split, false);        hard_assert(count == msg_len - split);        buf[count] = '\0';        printf("Read  at 0x%02X: '%s'\n", mem_address + split, buf);        hard_assert(memcmp(buf, msg + split, msg_len - split) == 0);        puts("");        sleep_ms(2000);    }}#endifint main() {    stdio_init_all();#if !defined(i2c_default) || !defined(PICO_DEFAULT_I2C_SDA_PIN) || !defined(PICO_DEFAULT_I2C_SCL_PIN)#warning i2c / slave_mem_i2c example requires a board with I2C pins    puts("Default I2C pins were not defined");    return 0;#else    puts("\nI2C slave example");    setup_slave();    run_master();#endif}

Code:

cmake_minimum_required(VERSION 3.13)include(pico_sdk_import.cmake)project(slave_mem_project C CXX ASM)set(CMAKE_C_STANDARD 11)set(CMAKE_CXX_STANDARD 17)pico_sdk_init()add_executable(slave_mem_i2c    slave_mem_i2c.c    )pico_enable_stdio_usb(slave_mem_i2c 1)pico_enable_stdio_uart(slave_mem_i2c 0)target_link_libraries(slave_mem_i2c    pico_i2c_slave    hardware_i2c    pico_stdlib    )pico_add_extra_outputs(slave_mem_i2c)