How to use the DIO SPI on ESP32 with espidf? - esp32

Question

I'm trying to use the DIO SPI mode on the ESP32 with the espidf (version 4.4).
But I encountered problems.
I have a ram device (ref 23LC1024) than can be accessed with several modes (single, dual, quad).
The single mode works perfectly (can write and read back)
The dual mode creates problems.
Here is how I configure the SPI bus (same setup for single or dual mode)
memset(&config, 0, sizeof(spi_bus_config_t));
config.mosi_io_num = MOSI_PIN;
config.miso_io_num = MISO_PIN;
config.sclk_io_num = SCLK_PIN;
config.quadwp_io_num = -1; // -1 not used
config.quadhd_io_num = -1; // -1 not used
config.flags = SPICOMMON_BUSFLAG_DUAL | SPICOMMON_BUSFLAG_MASTER;
spi_bus_initialize(VSPI_HOST, &config, SPI_DMA_DISABLED); // 0 DMA not used
Now the setup for the device (same setup for single mode or dual):
spi_device_interface_config_t devcfg = {
.clock_speed_hz = freq,
.command_bits = 8,
.address_bits = 24,
.dummy_bits = 8,
.mode = 0, // SPI MODE 0
.flags = 0,
.spics_io_num = _cs,
.queue_size = 1,
.pre_cb = NULL,
.post_cb = NULL};
ESP_ERROR_CHECK(spi_bus_add_device(VSPI_HOST, &devcfg, &data_Ram));
Now the setup for the transaction:
spi_transaction_t t;
memset(&t, 0, sizeof(t)); // Zero out the transaction
t.cmd = WRITE;
t.tx_buffer = data;
t.rx_buffer = NULL;
t.addr = address;
t.length = size * 8;
if (USE_DIO) // configure these flags in case of DIO
t.flags = SPI_TRANS_MODE_DIO | SPI_TRANS_MULTILINE_ADDR | SPI_TRANS_MULTILINE_CMD;
ESP_ERROR_CHECK(spi_device_transmit(data_Ram, &t)); // Transmit!
It works nicely in the single mode but with the dual mode I got the error:
E (1618) spi_master: check_trans_valid(699): Incompatible when setting to both multi-line mode and half duplex mode
Does it mean I cannot use DIO in half duplex mode with the SPI master library?
Is there something I should change in my setup ?
I tried to specify the SPI_DEVICE_HALFDUPLEX flag in the spi_device_interface_config_t. Does not help.
Unfortunately I did not find any example on internet.
Thanks for your heads up!

Answer 1

E (1618) spi_master: check_trans_valid(699): Incompatible when setting to both multi-line mode and half duplex mode means that you cannot use MISO and MOSI for transfering (multiline) AND use them at the same time (full duplex).
Set your device to half duplex to fix the problem:
spi_device_interface_config_t devcfg = {
.flags = SPI_DEVICE_HALFDUPLEX,
...
};
In my experience, SPI_TRANS_MULTILINE_ADDR doesn't work, at least with spi_device_transmit.
If your ram device allows it, try without the "multilined" address and command.