MCP7940 device tree implementation

[ljch]

Hi I am receiving the error "Linking C executable zephyr\zephyr_pre0.elf FAILED:" which I have found is linked to the mcp7940 device tree node through the error code " undefined reference to `__device_dts_ord_57'" in the device_generated.h file. I want to include in the device tree the interrupt that the mcp7940  on gpio 0 21 of the NRF52805 but I'm not sure if this is best practice or not. How do I solve this error and include the gpio interrupt in the device tree?

Here is the device tree node for the MCP7940n and the corresponding device tree binding.

Device Tree node

&i2c0 {
    status = "okay";
    pinctrl-0 =<&i2c0_default>;
    pinctrl-1 =<&i2c0_sleep>;
    pinctrl-names = "default","sleep";
    clock-frequency = <100000>;
    
    mcp7940n: mcp7940n@6f {
        compatible = "microchip,mcp7940n";
        reg = <0x6f>;
        label = "MCP7940N_RTC";
        //int-gpios = <&gpio0 21 GPIO_ACTIVE_LOW>;  // Use actual GPIO pin where interrupt is connected
    };
};

.yaml binding

#
# Copyright (c) 2021 Laird Connectivity
# Copyright (c) 2023 Nordic Semiconductor ASA
#
# SPDX-License-Identifier: Apache-2.0
#

description: Microchip MCP7940N I2C RTC with battery-backed SRAM

compatible: "microchip,mcp7940n"

include: i2c-device.yaml

properties:
  reg:
    type: array
    description: |
      The I2C address of the device 0x6F
      

[Simonr]

Hi

So, the device_dts_ord_xx error in itself doesn't tell us much other than that the device tree structure (dts) is missing something. Please check out the file in build\zephyr\include\generated\devicetree_generated.h and check what the number 57 corresponds to. You can check out the DevAcademy lesson on troubleshooting the devicetree here: https://academy.nordicsemi.com/courses/nrf-connect-sdk-intermediate/lessons/lesson-2-debugging/topic/troubleshooting-the-devicetree/ 

Best regards,

Simon

[ljch]

Hi Simon, I did check line 57 and it said it corresponded to the MCP7940 RTC. I ended up scrapping the custom driver and just used the generic i2c driver api.