#ifdef CONFIG_M5CORES3_SPI_CONFLICT_FIX
#define M5CORES3_SPI_CONFIG_FIX_MISO_PIN 35

void sx127x_spi_pre_transfer_m5cores3_fix_callback(spi_transaction_t* t) {
    // before a SPI transaction is started, we need to change the driving direction
    // of the DC pin in the CoreS3 (the CoreS3 uses the MISO pin as the DC pin and 
    // configures it as an output ping which conflicts with other SPI devices on the bus)
    
    // set gpio direction for MISO pin to input
    gpio_set_direction(M5CORES3_SPI_CONFIG_FIX_MISO_PIN, GPIO_MODE_INPUT);
}

void sx127x_spi_post_transfer_m5cores3_fix_callback(spi_transaction_t* t) {
    // undo pin direction change after SPI transaction is done

    // set gpio direction for MISO pin back to output
    gpio_set_direction(M5CORES3_SPI_CONFIG_FIX_MISO_PIN, GPIO_MODE_OUTPUT);
}
#endif

sx127x_handle_t sx127x_init(const sx127x_modem_config_t* modem_config)
{
    // ...

    // Configure SPI device
    spi_device_interface_config_t spi_dev_cfg = {
        .clock_speed_hz = 9000000,  // 9MHz
        .mode = 0,
        .spics_io_num = modem_config->cs_gpio,
        .queue_size = 7,
        .flags = 0,
        #ifdef CONFIG_M5CORES3_SPI_CONFLICT_FIX
        .pre_cb = sx127x_spi_pre_transfer_m5cores3_fix_callback,
        .post_cb = sx127x_spi_post_transfer_m5cores3_fix_callback
        #endif
    };
    ret = spi_bus_add_device(spi_host, &spi_dev_cfg, &device->spi);
    if (ret != ESP_OK) {
        ESP_LOGE(TAG, "Failed to add SPI device");
        vSemaphoreDelete(device->spi_mutex);
        free(device);
        return NULL;
    }

    // ...
}

I can now use both the display and the sx1276 at the same time on the M5Stack CoreS3.

Thanks again for your assistance!

I think it has been fixed by M5Stack. Check out this example - works for me.

BTW: my example does not work anymore as M5.Lcd.getSPIinstance() no longer exists in M5CoreS3 library.

Thanks
Felix

In ESP-IDF there is a pre_cb and post_cb (callback configurations) that can be configured with the SPI device when it's registered on the bus. This should allow me to accommodate the DC/MISO reconfiguration in a bit more automated of a way.

Thanks again for your help!

I am not sure it is still valid, but last year I encountered a similar issue when trying to use the LCD and the SD card together with an M5CoreS3.

Maybe the solution I found at the time might be helpful for your situation as well.

Note: I cannot test this myself as I lack the necessary hardware, e.g. I do not have a LoRa868 v1.1.

Thanks
Felix