drivers: dac: Add drivers for TI DAC family X311 on SPI bus #90811

Snap-A · 2025-05-29T16:00:08Z

Summary

This PR submits the device driver code for the Texas Instrument chip family DAC N311, with N indicating the resolution (see below).
These chips provide a single output channel and support "power mode" selection by reserving the two MSB values for this.
There is a single "register" that is updated with each 16-bit write to the chip via SPI.

Code Changes

The driver was code was modeled after DAC drivers for other chip families, where different resolutions are supported.

The new Kconfig.tx311 enables the driver when a matching entry is added to the device tree;
The new driver (dac_tx311.c) processes the device tree to set the correct resolution value;

Chip Resolution

5311 8 bits

6311 10 bits

7311 12 bits

8311 14 bits
The related YAML files use a "base" file to share the configuration "schema".
The configuration adds the property power-down-mode to set the power mode bits.

Tests

Normal Mode

This driver was developed to control the TI 6311 DAC chip that is part of an external PCB. The SPI bus was connected to a Raspberry Pico W and a sample program was created to generate a "saw tooth" signal with a period of a few seconds and the power mode set to "normal".

A oscilloscope was connected to the Vout pin of the chip to confirm the full voltage range, 0 to 3.3 V, is produced.

Resistor to GND Mode

The power mode was set to "power-down-100k" and the test program was recompiled. The DAC output shows no saw-tooth signal.

sonarqubecloud · 2025-05-29T16:47:06Z

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

github-actions · 2025-07-29T00:45:45Z

This pull request has been marked as stale because it has been open (more than) 60 days with no activity. Remove the stale label or add a comment saying that you would like to have the label removed otherwise this pull request will automatically be closed in 14 days. Note, that you can always re-open a closed pull request at any time.

martinjaeger

Sorry for the late review. I missed this PR. In the future, just feel free to ping the maintainer if you don't get any feedback after a few weeks.

See my comments below.

martinjaeger · 2025-07-31T14:52:59Z

drivers/dac/dac_tx311.c

+	if ((config->resolution > DACX311_MAX_RESOLUTION) ||
+			(config->resolution < DACX311_MIN_RESOLUTION)) {
+		LOG_ERR("Unsupported resolution %d", config->resolution);
+		return -ENOTSUP;
+	}
+
+	if (config->power_down_mode > 3) {
+		LOG_ERR("Unsupported power mode %d", config->power_down_mode);
+		return -ENOTSUP;
+	}


This could already be checked at build-time with BUILD_ASSERT macro.

I adjusted the code to use two BUILD_ASSERT macros. The check on the resolution value was removed, since it is "hard-coded" for each variant (see end of file).

martinjaeger · 2025-07-31T14:54:44Z

drivers/dac/dac_tx311.c

+	if (1000 * config->max_freq_khz < config->bus.config.frequency) {
+		LOG_ERR("SCLK frequency too high: '%d' Hz", config->bus.config.frequency);
+		return -ENOTSUP;
+	}


I guess we can't check this at build-time. But can we put it into a driver init function, so that it's already checked before entering main?

Added an init function, but this check became a BUILD_ASSERT macro since it represents a chip specific max frequency that is not changing.

martinjaeger · 2025-07-31T14:56:24Z

drivers/dac/dac_tx311.c

+	/* Set bit resolution for this chip variant */
+	data->resolution = config->resolution;
+
+	/* Set the power mode (shifted to upper bits) */
+	data->power_down_mode = FIELD_PREP(BIT_MASK(2) << DACX311_MAX_RESOLUTION,
+			config->power_down_mode);


This should also go into a driver init function.

Agree, and changed the code.

martinjaeger · 2025-07-31T15:01:52Z

drivers/dac/dac_tx311.c

+	data->configured |= BIT(channel_cfg->channel_id);
+
+	/* Set bit resolution for this chip variant */
+	data->resolution = config->resolution;


Should this not be like this?

Suggested change

data->resolution = config->resolution;

data->resolution = channel_cfg->resolution;

And in this case, we should also check if the desired resolution is supported by the chip.

martinjaeger · 2025-07-31T15:03:11Z

drivers/dac/dac_tx311.c

+
+struct dacx311_config {
+	struct spi_dt_spec bus;
+	uint8_t  resolution;


It looks like this is actually the max resolution supported by the chip, but we can configure it for lower resolution, right? Should we then name it max_resolution to make the meaning more clear?

Each chip variant has a fixed resolution. The entry in this struct is present in order to use the same code logic for the different chip variants. This value is different for each variant.

martinjaeger · 2025-07-31T15:09:58Z

Please also add the driver to tests/drivers/build_all/dac/app.overlay to make sure it's built in CI.

Snap-A · 2025-08-01T13:43:12Z

@martinjaeger : Thanks for the review! I will first resolve the merge conflict and then work on your comments.

sonarqubecloud · 2025-08-01T15:15:58Z

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

sonarqubecloud · 2025-09-18T21:46:15Z

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

martinjaeger

My previous comments were not addressed yet.

Snap-A · 2025-11-16T17:43:45Z

Did not have time to work in this over the last months. Hopefully, I can in the next weeks.

Snap-A · 2025-11-22T16:45:12Z

Please also add the driver to tests/drivers/build_all/dac/app.overlay to make sure it's built in CI.

Working on this, next.

Add shared code in 'dac_tx311.c' and configuration files. Support power mode bits via configuration. Signed-off-by: Andreas Wolf <[email protected]>

sonarqubecloud · 2025-12-07T00:39:18Z

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

Snap-A marked this pull request as ready for review May 29, 2025 17:16

github-actions bot added area: DAC Digital-to-Analog Converter platform: TI SimpleLink Texas Instruments SimpleLink MCU labels May 29, 2025

github-actions bot requested review from martinjaeger, vaishnavachath and vanti May 29, 2025 17:16

github-actions bot assigned martinjaeger May 29, 2025

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martinjaeger removed the Stale label Jul 31, 2025

Snap-A force-pushed the add_ti_x311_driver branch from a048710 to cb4da7e Compare August 1, 2025 15:11

Snap-A force-pushed the add_ti_x311_driver branch from cb4da7e to d69d758 Compare September 18, 2025 21:42

kartben requested a review from martinjaeger October 17, 2025 19:56

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Snap-A force-pushed the add_ti_x311_driver branch from d69d758 to 1bb6885 Compare November 16, 2025 16:46

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Snap-A force-pushed the add_ti_x311_driver branch from 1bb6885 to fe4d7b1 Compare November 22, 2025 16:37

Snap-A force-pushed the add_ti_x311_driver branch from fe4d7b1 to c25cc8c Compare December 6, 2025 21:52

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drivers: dac: Add drivers for TI DAC family X311 on SPI bus

dc0dc90

Add shared code in 'dac_tx311.c' and configuration files. Support power mode bits via configuration. Signed-off-by: Andreas Wolf <[email protected]>

Snap-A force-pushed the add_ti_x311_driver branch from c25cc8c to dc0dc90 Compare December 7, 2025 00:12

	data->resolution = config->resolution;
	data->resolution = channel_cfg->resolution;

Chip	Resolution
5311	8 bits
6311	10 bits
7311	12 bits
8311	14 bits

drivers: dac: Add drivers for TI DAC family X311 on SPI bus #90811

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drivers: dac: Add drivers for TI DAC family X311 on SPI bus #90811

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Snap-A commented May 29, 2025

Summary

Code Changes

Tests

Normal Mode

Resistor to GND Mode

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sonarqubecloud bot commented May 29, 2025

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github-actions bot commented Jul 29, 2025

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martinjaeger commented Jul 31, 2025

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Snap-A commented Aug 1, 2025

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sonarqubecloud bot commented Aug 1, 2025

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sonarqubecloud bot commented Sep 18, 2025

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Snap-A commented Nov 16, 2025

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sonarqubecloud bot commented Dec 7, 2025

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