How to connect other sensor to nrf9160 (i2c and GPIO)

[Liza]

Hi, 

I want to connect LDC2114 to nRF9160. I write the nrf9160dk_nrf9160_ns.overlay and the astri,ldc2114.yaml. I don't know how to set GPIOs in &i2c1 - ldc2114: ldc2114@2a which are the output pins of LDC2114 and input pins of nRF9160.

Fullscreen 1462.nrf9160dk_nrf9160_ns.overlay.txt Download

/ {
	/* Map the devices to the aliases of the application. */ 
	aliases {	
		ldc-sensor = &ldc2114;
	};
	
};

&i2c1 {
    compatible = "nordic,nrf-twim";
    #address-cells = < 0x1 >;
    #size-cells = < 0x0 >;
    reg = < 0x9000 0x1000 >;
    // clock-frequency = < 0x186a0 >;
    clock-frequency = <I2C_BITRATE_STANDARD>;
    interrupts = < 0x9 0x1 >;
    status = "okay";
    pinctrl-0 = < &i2c1_default >;
    pinctrl-1 = < &i2c1_sleep >;
    pinctrl-names = "default", "sleep";
    ldc2114: ldc2114@2a{
        compatible = "astri,ldc2114";   //binding
        status = "okay";
        reg = < 0x2a >;
        label = "LDC2114";
        gpio-controller;
        #gpio-cells = < 0x2 >;
        intb-gpios = < &gpio0 25 0 >; // LDC2114 INTB pin -> nrf9160 INPUT P0.25
        in0-gpios = < &gpio0 24 0 >;  // LDC2114 OUT0 pin -> nrf9160 INPUT P0.24
        in1-gpios = < &gpio0 23 0 >;  // LDC2114 OUT1 pin -> nrf9160 INPUT P0.23
        in2-gpios = < &gpio0 22 0 >;  // LDC2114 OUT2 pin -> nrf9160 INPUT P0.22
        in3-gpios = < &gpio0 21 0 >;  // LDC2114 OUT3 pin -> nrf9160 INPUT P0.21
    };
};

&i2c2 { 
	status = "disabled";
};

&pinctrl {
	i2c1_default: i2c1_default {
		group1 {
			psels = <NRF_PSEL(TWIM_SDA, 0, 30)>,
				    <NRF_PSEL(TWIM_SCL, 0, 31)>;
		};
	};

	i2c1_sleep: i2c1_sleep {
		group1 {
			psels = <NRF_PSEL(TWIM_SDA, 0, 30)>,
				    <NRF_PSEL(TWIM_SCL, 0, 31)>;
			low-power-enable;
		};
	};
};

Fullscreen 2308.astri,ldc2114.yaml.txt Download

# Copyright (c) 2018, Peter Bigot Consulting, LLC
# SPDX-License-Identifier: Apache-2.0

description: Sensor LDC2114

compatible: "astri,ldc2114"

include: [sensor-device.yaml, i2c-device.yaml, gpio-controller.yaml, base.yaml]

properties:
  reg:
    required: true

  #alert-gpios:

  "#gpio-cells":
    const: 2

  intb-gpios:
    type: phandle-array
    description: |
      LDC2114 INTB pin -> nrf9160 INPUT P0.25

  in0-gpios:
    type: phandle-array
    description: |
      LDC2114 OUT0 pin -> nrf9160 INPUT P0.24

  in1-gpios:
    type: phandle-array
    description: |
      LDC2114 OUT1 pin -> nrf9160 INPUT P0.23

  in2-gpios:
    type: phandle-array
    description: |
      LDC2114 OUT2 pin -> nrf9160 INPUT P0.22

  in3-gpios:
    type: phandle-array
    description: |
      LDC2114 OUT3 pin -> nrf9160 INPUT P0.21

gpio-cells:
  - pin
  - flags

Also, What else should I do in order to connect the devices?

Best regards,

Liza

[Vidar Berg]

Hi Liza,

It looks like you have configured everything correctly in your Devicetree overlay. Are you getting build errors, or does it fail when you try to run the application?

Best regards,

Vidar

[Liza]

Hi Vidar Berg,

I cannot call gpios from ldc2114 Devicetree. Since the gpios are input pins, so I call them from node gpio0 "dev_gpio = device_get_binding(DEVICE_DT_NAME(DT_NODELABEL(gpio0)));" and it works.

Do you know how to call gpios from node ldc2114?

Best regards,

Liza

[Liza]

Hi Vidar,

Vidar Berg said:

Please note that DEVICE_DT_GET or device_get_binding() should be used in application code to verify whether a driver has been successfully initialized when working with a Zephyr driver which are initialized at startup before the program reaches main().

Could I use any existing Zephyr driver without writing the driver by myself in my case (connect LDC2114 to nRF9160DK with I2C)? Because it is difficult to write it. If not, do you have any tutorial about writing my own driver?

Best regards,

Liza

[Vidar Berg]

Hi Liza,

Zephyr does not include a driver for this specific device, unfortunately. You can use the Zephyr i2c driver api directly in your application, or create your own Zephyr driver following the Zephyr driver model. There are many blogs and tutorials for creating zephyr driver. This one for example: https://blog.golioth.io/adding-an-out-of-tree-sensor-driver-to-zephyr/ 

Best regards,

Vidar

[Liza]

Hi Vidar,

Vidar Berg said:

This one for example: https://blog.golioth.io/adding-an-out-of-tree-sensor-driver-to-zephyr/ 

Thanks. I will follow it to write my driver.

When build for the raw project example-application, it also has error on "DEVICE_DT_GET" of "sensor = DEVICE_DT_GET(DT_NODELABEL(examplesensor0));". It' confused. I don't know why.

This is the build log:

Best regards,

Liza

[Vidar Berg]

Hi Liza,

Do you have a node named 'examplensor0' in your devicetree? You can check by reviewing the generated zephyr.dts file in your build folder. It might be simpler to use the Zephyr I2C API directly in your application instead of creating a new driver based on the Zephyr driver model. I coworker made a sample that does this with the Zephyr SPI driver here: https://github.com/too1/ncs-spi-master-slave-example 

Best regards,

Vidar

[Liza]

Hi Vidar,

It's better if I don't need to write driver.

Do you know how to write data to the register address of LDC2114 through I2C? For example, the LDC2114 address is 0x2a, the output pin polarity can be configured in Register 0x1C.

Thanks,

Liza

[Vidar Berg]

Hi Liza,

This devacademy course explains how you can use the driver API from your application: https://academy.nordicsemi.com/courses/nrf-connect-sdk-fundamentals/lessons/lesson-6-serial-com-i2c/topic/i2c-driver/.  You can use i2c_write_dt(), or  i2c_write() to set this register on your sensor.

Best regards,

Vidar

[Liza]

Hi Vidar,

I use i2c_burst_write() and i2c_burst_read() to write and read value. I write 0x10 to LDC_REG_RESET (reg address 0x0a), but read the value 0 from LDC_REG_RESET (reg address 0x0a). Both two methods return value 0 which indicates that write/read successful.

Fullscreen i2c.txt Download

    error = 1;
    config[0] = 0x10;
    error = i2c_burst_write(dev_i2c,i2c_dt_ldc2114.addr,LDC_REG_RESET,config, sizeof(config));
    if(error != 0){
        printk("LDC_REG_RESET: Failed to write 0x%x to address 0x0%x. \n\r", config[0],LDC_REG_RESET);
    }
    else{
        error = 1;
        printk("LDC_REG_RESET: Successful write 0x%x to address 0x0%x. \n\r", config[0],LDC_REG_RESET);
    }
    printk("size of config=%d\n",sizeof(config));
    printk("1: config[0]=%x\n",config[0]);

        k_sleep(K_MSEC(100));

        error = i2c_burst_read(dev_i2c,i2c_dt_ldc2114.addr,LDC_REG_RESET,config_read, sizeof(config_read));
        if(error != 0){
            printk("LDC_REG_STATUS: Failed to read data at address 0x0%x. \n\r", LDC_REG_RESET);
        }
        else{
            error = 1;
            printk("LDC_REG_STATUS: Successful read value %x at address 0x0%x. \n\r", config_read[0],LDC_REG_RESET);
        }
    printk("2: config_read[0]=%x\n",config_read[0]);



output:
LDC_REG_RESET: Successful write 0x10 to address 0x0a. 
size of config=1
1: config[0]=10
LDC_REG_STATUS: Successful read value 0 at address 0x0a. 
2: config_read[0]=0

Thanks,

Liza

[Vidar Berg]

Hi Liza,

I have not worked with this IC before, but I had a look at the datasheet, and it seems like the RESET register is supposed to be 0 after reset. Section 7.3.6 also outlines a special handshake process to perform the write sequence. Have you tried reading the status register instead?

[Liza]

Hi Vidar,

You are right! The RESET register is supposed to be 0 after reset. I read the status register and get what I want.

But it seems that i2c_burst_write() and i2c_burst_read() have byte limit?

I try to write 27 bytes buff to LDC_REG_CHAN_EN(0x0c) and the writing error occurs. Then I reduce the buff to 15 bytes, and write & read success.

Fullscreen i2c_burst_write.txt Download

------------------------write 27 bytes to LDC_REG_CHAN_EN (0x0c):--------------------------------------------------

uint8_t configbuf[]={                            0xFF, 0x03, 0x3F, 0x00, //0x0C ~0x0F
                0x3F, 0x01, 0x3F, 0x07, 0x3F, 0x07, 0x00, 0x02, //0x10 ~0x17
                0x03, 0x00, 0xff, 0x00, 0xFF, 0x00, 0x00, 0x00, //0x18 ~0x1F
                0xA7, 0x00, 0xA7, 0x00, 0xA7, 0x00, 0xA7};      //0x20
uint8_t cfgcomp[32];

        k_sleep(K_MSEC(2));
        error = i2c_burst_write(dev_i2c,i2c_dt_ldc2114.addr,LDC_REG_CHAN_EN,configbuf, 27);
        if(error!=0){
            printk("\n--ERROR: LDC_REG_CHAN_EN: Failed to write data at address 0x0%x.-- \n\r", LDC_REG_CHAN_EN);
            return;
        } 
        k_sleep(K_MSEC(2));
        error = i2c_burst_read(dev_i2c,i2c_dt_ldc2114.addr,LDC_REG_CHAN_EN,cfgcomp, 27);
        if(error!=0){
            printk("\n--ERROR: LDC_REG_CHAN_EN: Failed to read data at address 0x0%x.-- \n\r", LDC_REG_CHAN_EN);
            return;
        } 
        for(i=0;i<27;i++){
            printk("configbuf[%d] = %x   ", i, configbuf[i]);
            printk("cfgcomp[%d] = %x\n", i, cfgcomp[i]);
            if(cfgcomp[i] != configbuf[i]){
                printk("\n--ERROR: LDC_REG_CHAN_EN--\n");
                //return;
            }
        }


------------------------output：-------------------------------------------
--ERROR: LDC_REG_CHAN_EN: Failed to write data at address 0x0c.--




--------------------------After reducing the buff to 15 bytes:------------------------------

uint8_t configbuf[]={                            0xFF, 0x03, 0x3F, 0x00, //0x0C ~0x0F
                0x3F, 0x01, 0x3F, 0x07, 0x3F, 0x07, 0x00, 0x02, //0x10 ~0x17
                0x03, 0x00, 0xff, 0x00, 0xFF, 0x00, 0x00, 0x00, //0x18 ~0x1F
                0xA7, 0x00, 0xA7, 0x00, 0xA7, 0x00, 0xA7};      //0x20
uint8_t cfgcomp[32];

        k_sleep(K_MSEC(2));
        error = i2c_burst_write(dev_i2c,i2c_dt_ldc2114.addr,LDC_REG_CHAN_EN,configbuf, 15);
        if(error!=0){
            printk("\n--ERROR: LDC_REG_CHAN_EN: Failed to write data at address 0x0%x.-- \n\r", LDC_REG_CHAN_EN);
            return;
        } 
        k_sleep(K_MSEC(2));
        error = i2c_burst_read(dev_i2c,i2c_dt_ldc2114.addr,LDC_REG_CHAN_EN,cfgcomp, 15);
        if(error!=0){
            printk("\n--ERROR: LDC_REG_CHAN_EN: Failed to read data at address 0x0%x.-- \n\r", LDC_REG_CHAN_EN);
            return;
        } 
        for(i=0;i<15;i++){
            printk("configbuf[%d] = %x   ", i, configbuf[i]);
            printk("cfgcomp[%d] = %x\n", i, cfgcomp[i]);
            if(cfgcomp[i] != configbuf[i]){
                printk("\n--ERROR: LDC_REG_CHAN_EN--\n");
                //return;
            }
        }


------------------output：----------------
configbuf[0] = ff   cfgcomp[0] = ff
configbuf[1] = 3   cfgcomp[1] = 3
configbuf[2] = 3f   cfgcomp[2] = 3f
configbuf[3] = 0   cfgcomp[3] = 0
configbuf[4] = 3f   cfgcomp[4] = 3f
configbuf[5] = 1   cfgcomp[5] = 1
configbuf[6] = 3f   cfgcomp[6] = 3f
configbuf[7] = 7   cfgcomp[7] = 7
configbuf[8] = 3f   cfgcomp[8] = 3f
configbuf[9] = 7   cfgcomp[9] = 7
configbuf[10] = 0   cfgcomp[10] = 0
configbuf[11] = 2   cfgcomp[11] = 2
configbuf[12] = 3   cfgcomp[12] = 3
configbuf[13] = 0   cfgcomp[13] = 0
configbuf[14] = ff   cfgcomp[14] = ff

So I split the 27 bytes to 12 bytes and 15 bytes, then write and read successfully.

Thanks,

Liza

[Vidar Berg]

Hi Liza,

You may get more information about why the write failed by enabling CONFIG_LOG to get the logs from the nrfx I2C driver. The TWIM hardware supports sending up to 4096 bytes, but the data may be NACKed by the slave, which will cause the write transaction to be aborted. From the datasheet it seems that the LDC_REG_CHAN_EN register is only 1 byte.

Best regards,

Vidar