Can't get SPI communication to work on the nrf5340-dk

RE: Can't get SPI communication to work on the nrf5340-dk

blakbu — Sat, 20 Aug 2022 18:04:26 GMT

Hey,

Can you share your schematics? I couldn't find any resources for using nrf5340 with ads1299. If you can share your schematic, that would be really helpful.

RE: Can't get SPI communication to work on the nrf5340-dk

MickyT — Tue, 15 Feb 2022 16:33:46 GMT

No worries, thank you for replying.

I did call `nrfx_gpiote_in_init`, but I see now that I didn't copy it correctly in my previous post, sorry about that. I will edit that post and add my entire file below (see line 75 for the init function).

#include "ADS1299.h"
#include <zephyr.h>
#include <sys/printk.h>
#include <nrfx_spim.h>
#include <device.h>
#include <devicetree.h>
#include <drivers/gpio.h>

#ifndef POLL_DREADY
    #include <nrfx_gpiote.h>
#endif

#define SPI_INSTANCE 2

#define PIN_SCK NRF_GPIO_PIN_MAP(0, 8)
#define PIN_MOSI NRF_GPIO_PIN_MAP(0, 9)
#define PIN_MISO NRF_GPIO_PIN_MAP(0, 10)
#define PIN_CS NRF_GPIO_PIN_MAP(0, 2)

#define PIN_DRDY NRF_GPIO_PIN_MAP(0, 7)

#define COMMAND_WAKEUP 0x02
#define COMMAND_STANDBY 0x04
#define COMMAND_RESET 0x06
#define COMMAND_START 0x08
#define COMMAND_STOP 0x0A
#define COMMAND_RDATA 0x12
#define COMMAND_RDATAC 0x10
#define COMMAND_SDATAC 0x11
#define COMMAND_RREG 0b00100000
#define COMMAND_WREG 0b01000000

volatile enum state_t {idle, send_command, receive_data, processing_data} state = idle;
bool new_data_available = false;

static const nrfx_spim_t m_spi = NRFX_SPIM_INSTANCE(SPI_INSTANCE);
uint8_t rx_buffer[27], tx_buffer[8];
uint8_t sample_number = 0;

const struct device *gpio_dev_0, *gpio_dev_1;

inline int32_t buffer_to_channel(uint8_t id);
bool ADS1299_receive_data();
ADS1299_data_t ADS1299_convert_data();

#ifndef POLL_DREADY
    void data_ready_handler(nrfx_gpiote_pin_t pin, nrf_gpiote_polarity_t action);
#endif

void spim_event_handler(nrfx_spim_evt_t const *p_event, void *p_context) {
    switch (p_event->type)
    {
    case NRFX_SPIM_EVENT_DONE:
        if(state == receive_data) {
            new_data_available = true;
        }
        gpio_pin_set(gpio_dev_1, 1, 1);
        state = idle;
        break;
    
    default:
        break;
    }
    return;
}

#ifndef POLL_DREADY
void data_ready_handler(nrfx_gpiote_pin_t pin, nrf_gpiote_polarity_t action) {
    if(pin == PIN_DRDY && action == NRF_GPIOTE_POLARITY_HITOLO) {
        ADS1299_receive_data();
    }
}
#endif

bool ADS1299_init() {
    nrfx_spim_config_t config = NRFX_SPIM_DEFAULT_CONFIG(PIN_SCK, PIN_MOSI, PIN_MISO, NRFX_SPIM_PIN_NOT_USED);
    config.frequency = NRF_SPIM_FREQ_125K;
    config.ss_active_high = false;
    config.bit_order = SPIM_CONFIG_ORDER_MsbFirst;
    config.mode = NRF_SPIM_MODE_1;
    
    nrfx_spim_uninit(&m_spi);
    int err = nrfx_spim_init(&m_spi, &config, spim_event_handler, NULL);

    if(err == NRFX_SUCCESS) {
        printk("SPI init success\r\n");
    } else {
        printk("FAIL: SPI init failed: %d\r\n", err);
        return false;
    }
    
    gpio_dev_0 = device_get_binding("GPIO_0");
    gpio_dev_1 = device_get_binding("GPIO_1");

    if (gpio_dev_0 == NULL) {
		return false;
	}

    if (gpio_dev_1 == NULL) {
		return false;
	}

    #ifdef POLL_DREADY
        printk("Configure DREADY pin\r\n");
        err = gpio_pin_configure(gpio_dev_0, 7, GPIO_INPUT);
        printk("Return config DREADY pin: %d\r\n", err);
    #else
        // Interrupt
        if(!nrfx_gpiote_is_init()) {
            err = nrfx_gpiote_init(6);

            if(err == NRFX_SUCCESS) {
                printk("Pin IRQ init success\r\n");
            } else {
                printk("FAIL: pin IRQ init failed: %d\r\n", err);
                return false;
            }
        }

        nrfx_gpiote_in_config_t irq_config = NRFX_GPIOTE_CONFIG_IN_SENSE_TOGGLE(false); // TODO: what is argument?
        err = nrfx_gpiote_in_init(PIN_DRDY, &irq_config, data_ready_handler);

        if(err == NRFX_SUCCESS) {
            printk("Pin IRQ config success\r\n");
        } else {
            printk("FAIL: pin IRQ config failed: %d\r\n", err);
            return false;
        }
    #endif
    

	gpio_pin_configure(gpio_dev_1, 1, GPIO_OUTPUT);
    gpio_pin_set(gpio_dev_1, 1, 1);

    #ifndef POLL_DREADY
        nrfx_gpiote_in_event_enable(PIN_DRDY, true);
    #endif

    return true;
}

void poll_dready() {
    if(gpio_pin_get(gpio_dev_0, 7) == 0) {
        ADS1299_receive_data();
    }
}

int spi_transfer(const nrfx_spim_xfer_desc_t *desc) {
    gpio_pin_set(gpio_dev_1, 1, 0);
    return nrfx_spim_xfer(&m_spi, desc, 0);
}

bool ADS1299_send_command(uint8_t command) {
    if(state == idle) {
        nrfx_spim_xfer_desc_t spim_xfer_desc = NRFX_SPIM_XFER_TX(tx_buffer, 1);
        spim_xfer_desc.p_rx_buffer = NULL;
        spim_xfer_desc.rx_length = 0;
        tx_buffer[0] = command;
        state = send_command;
        int err = spi_transfer(&spim_xfer_desc);
        if(err != NRFX_SUCCESS) {
            printk("send command err: %d\r\n", err);
        }
        return true;
    } else {
        return false;
    }
}

bool ADS1299_write_register(uint8_t address, uint8_t value) {
    if(state == idle) {
        nrfx_spim_xfer_desc_t spim_xfer_desc = NRFX_SPIM_XFER_TX(tx_buffer, 2);
        spim_xfer_desc.p_rx_buffer = NULL;
        spim_xfer_desc.rx_length = 0;
        tx_buffer[0] = (address & 0b00011111) | COMMAND_WREG;
        tx_buffer[1] = value;
        state = send_command;
        int err = spi_transfer(&spim_xfer_desc);
        if(err != NRFX_SUCCESS) {
            printk("send command err: %d\r\n", err);
        }
        return true;
    } else {
        return false;
    }
}

bool ADS1299_send_start() {
    return ADS1299_send_command(COMMAND_START);
}

bool ADS1299_send_read_continuous() {
    return ADS1299_send_command(COMMAND_RDATAC);
}

bool ADS1299_send_reset() {
    return ADS1299_send_command(COMMAND_RESET);
}

bool ADS1299_receive_data() {
    if(state == idle) {
        state = receive_data;
        new_data_available = false;
        nrfx_spim_xfer_desc_t spim_xfer_desc = NRFX_SPIM_XFER_RX(rx_buffer, 27);
        spi_transfer(&spim_xfer_desc);
        return true;
    } else {
        return false;
    }
}

bool ADS1299_poll_new_data(ADS1299_data_t *data) {
    if(new_data_available) {
        new_data_available = false;
        state = processing_data;

        *data = ADS1299_convert_data();

        state = idle;

        return true;
    } else {
        return false;
    }
}

ADS1299_data_t ADS1299_convert_data() {
    /* Data structure: */
    /* 24 bit status */
    /*  - 1100 + LOFF_STATP(8 bit) + LOFF_STATN(8 bit) + GPIO(4 bit) */
    /* 8ch * 24 bits data */

    ADS1299_data_t data;
    
    data.lead_off_positive = rx_buffer[0] << 4;
    data.lead_off_positive |= (rx_buffer[1] & 0b11110000) >> 4;
    data.lead_off_negative = rx_buffer[1] << 4;
    data.lead_off_negative |= (rx_buffer[2] & 0b11110000) >> 4;

    data.gpio_0 = rx_buffer[2] & 0b00001000;
    data.gpio_1 = rx_buffer[2] & 0b00000100;
    data.gpio_2 = rx_buffer[2] & 0b00000010;
    data.gpio_3 = rx_buffer[2] & 0b00000001;

    data.channgel_0 = buffer_to_channel(0);
    data.channgel_1 = buffer_to_channel(1);
    data.channgel_2 = buffer_to_channel(2);
    data.channgel_3 = buffer_to_channel(3);
    data.channgel_4 = buffer_to_channel(4);
    data.channgel_5 = buffer_to_channel(5);
    data.channgel_6 = buffer_to_channel(6);
    data.channgel_7 = buffer_to_channel(7);

    return data;
}

inline int32_t buffer_to_channel(uint8_t id) {
    return rx_buffer[3 + id] << 16 | (rx_buffer[3 + id + 1] << 8) | rx_buffer[3 + id + 2];
}

bool get_spi_busy() {
    return state != idle;
}

RE: Can't get SPI communication to work on the nrf5340-dk

haakonsh — Mon, 14 Feb 2022 14:10:15 GMT

Sry for the late reply.

The PORT event has been fired, and the PORT event interrupt is enabled so that should also have fired.

Have you called gpiote_in_init() at all?

RE: Can't get SPI communication to work on the nrf5340-dk

MickyT — Wed, 09 Feb 2022 16:33:52 GMT

After a couple pauses I observed the following values:

So the only event generated is on the EVENTS_PORT and all the configs are 0, which corresponds to the result I am seeing, but not what I would expect given that the two init functions return a NRFX_SUCCESS.

Any ideas are appreciated, or if you know of a working example that would be great as well.

RE: Can't get SPI communication to work on the nrf5340-dk

haakonsh — Thu, 03 Feb 2022 12:53:38 GMT

[quote user="MickyT"]Do you have any idea what this issue might be?[/quote]

I don't know.

I think you should monitor the GPIOTE registers, specifically EVENTS_IN[n] and EVENTS_PORT during runtime(pause the debugger a few times after you've configured the GPIOTE channel).

You should also verify that the CONFIG[n] and INTENSET register is configured as intended. If you print out the values I can help you parse them.

RE: Can't get SPI communication to work on the nrf5340-dk

MickyT — Thu, 27 Jan 2022 11:45:35 GMT

I have made some progress on this issue. It turned out that there was either another bad connection or I needed to disconnect the Arduino I used as an analog in (simple oscilloscope), which gave me the following result.

So the signals look a lot cleaner and the sensor responds to commands, which is great.

Unfortunately now I am having some troubles getting the interrupt for the DRDY pin to work. I looked at some examples online, which resulted in the following (related) code:

#include <nrfx_gpiote.h>

#define PIN_DRDY NRF_GPIO_PIN_MAP(0, 7)

void data_ready_handler(nrfx_gpiote_pin_t pin, nrf_gpiote_polarity_t action) {
    if(pin == PIN_DRDY && action == NRF_GPIOTE_POLARITY_HITOLO) {
        ADS1299_receive_data();
    }
}

bool ADS1299_init() {
.
.
.
    if(!nrfx_gpiote_is_init()) {
        err = nrfx_gpiote_init(6);

        if(err == NRFX_SUCCESS) {
            printk("Pin IRQ init success\r\n");
        } else {
            printk("FAIL: pin IRQ init failed: %d\r\n", err);
            return false;
        }
    }
.
.   nrfx_gpiote_in_config_t irq_config = NRFX_GPIOTE_CONFIG_IN_SENSE_TOGGLE(false); // TODO: what is argument?
    err = nrfx_gpiote_in_init(PIN_DRDY, &irq_config, data_ready_handler);

    if(err == NRFX_SUCCESS) {
        printk("Pin IRQ config success\r\n");
    } else {
        printk("FAIL: pin IRQ config failed: %d\r\n", err);
        return false;
    }
.
    nrfx_gpiote_in_event_enable(PIN_DRDY, true);
}

When I put a breakpoint at the start of the `data_ready_handler` function and run in debug mode, I never trigger the breakpoint, while seeing multiple pulses on the input signal.

Do you have any idea what this issue might be?

Thanks again

EDIT: Forgot to copy a couple of lines of code.

RE: Can't get SPI communication to work on the nrf5340-dk

MickyT — Thu, 20 Jan 2022 15:13:35 GMT

Thank you for your reply.
I will have access to an oscilloscope next week, so I will check that and get back to you with that result.

For now it is just a simple test setup with jumper wires and a breadboard. I already swapped the cable ones, but I will try that again to eliminate that option.

The ground wire is connected between the 3 devices.

RE: Can't get SPI communication to work on the nrf5340-dk

haakonsh — Thu, 20 Jan 2022 11:10:16 GMT

If your clock and data line have inconsistent timings then your signal integrity is far too low. This is most likely a HW issue. Do you have access to an oscilloscope? An analog scope of the clock signal would be of great help.

Typical HW issues that affect signal integrity are poor grounding, parasitic/stray capacitance, and EMI.

[quote user=""]Remove connection to sensor (so only connected to LA), same result[/quote]

This is strange, I would expect the DK to have sufficient signal integrity in the layout. How do you connect the DA to the DK? Did you remember to connect the DA's ground lead to DK's ground?