TDA4VM: ADC driven continuous read mode cannot be turned on in kernel

Cherry Zhou said:

However, when setting the continuous read mode, it can be set successfully before, and finally it cannot be set successfully at echo 1 > /sys/bus/iio/devices/iio\:device0/buffer/enable, and it will prompt "-sh: echo: write error: Invalid argument

Cherry,

I didn't understand the above. Can you share the sequence of instructions that you are trying? I want to reproduce.

Best Regards,

Keerthy

Hi Keerthy,

Thank you for the support.

Keerthy J said:

Can you share the sequence of instructions that you are trying? I want to reproduce.

The device for the ADC is added to the device tree (the driver for the ADC is added), and then the device can be found under /sys/bus/iIO/devices/ to execute the following command: 

Cherry,

Can you share the device tree changes that you have made.w.r.t ADC8684?

If I understand correctly the adc ia external and not the one inside SoC?

Regards,

Keerthy

Hi Keerthy,

Keerthy J said:

Can you share the device tree changes that you have made.w.r.t ADC8684?

&main_spi1 {
pinctrl-names = "default";
pinctrl-0 = <&spi1_pins_default>;
status="okay";

adc@0 {
spi-max-frequency = <24000000>;
reg = <0>;
compatible = "ti,ads8684";
};
};

spi1_pins_default: spi1_pins_default {
pinctrl-single,pins = <
J721E_IOPAD(0x1dc, PIN_INPUT, 0) /* (Y1) SPI1_CLK */
J721E_IOPAD(0x1d4, PIN_INPUT, 0) /* (Y3) SPI1_CS0 */
J721E_IOPAD(0x1e0, PIN_INPUT, 0) /* (Y5) SPI1_D0 */
J721E_IOPAD(0x1e4, PIN_INPUT, 0) /* (Y2) SPI1_D1 */

>;
};

Keerthy J said:

If I understand correctly the adc ia external and not the one inside SoC?

The ADC is the ADS8684 and is communicated through SPI1.

Thanks and regards,

Cherry

Cherry,

As this is a custom board & ADC is connected via SPI1. I want to check if the probe function succeeds for this ADC?
How is the ADC conversion started? Does SPI needs to be involved to control the ADC?

- Keerthy

Hi Keerthy,

Keerthy J said:

I want to check if the probe function succeeds for this ADC?

The ADC probe was successful and the IIO:device0 has been established.

The ADS8684 is a 4-channel, SPI-controlled ADC for data acquisition. 

Thanks and regards,

Cherry

Cherry Zhou said:

The ADS8684 is a 4-channel, SPI-controlled ADC for data acquisition. 

So SPI also needs to be enabled to turn it on? Since this is a custom board and custom interface I want to understand more before I can give feedback.

- Keerthy