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drivers: dac: make output buffer for STM32 DAC configurable

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If an operational amplifier is used on the DAC output it is
preferrable to disable the DAC output buffer.

Signed-off-by: Benedikt Schmidt <benedikt.schmidt@embedded-solutions.at>
This commit is contained in:
Benedikt Schmidt 2023-05-09 14:06:55 +02:00 committed by Carles Cufí
parent 945d074ec0
commit 940ddba8bd
3 changed files with 18 additions and 2 deletions
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6
doc/releases/release-notes-3.4.rst
View file

@ -159,6 +159,12 @@ Changes in this release
registration function now returns a value which is 0 for success or a
negative error code if an error occurred.
* Added a new flag :c:struct:`dac_channel_cfg` ``buffered`` for DAC channels in
:c:struct:`dac_channel_cfg` to allow the configuration of the output buffer.
The actual interpretation of this depends on the hardware and is so far only
implemented for the STM32 DAC driver. Implicitly for this driver this changes
the default from being buffered to unbuffered.
Removed APIs in this release
============================

10
drivers/dac/dac_stm32.c
View file

@ -84,6 +84,7 @@ static int dac_stm32_channel_setup(const struct device *dev,
{
struct dac_stm32_data *data = dev->data;
const struct dac_stm32_cfg *cfg = dev->config;
uint32_t output_buffer;
if ((channel_cfg->channel_id - STM32_FIRST_CHANNEL >=
data->channel_count) ||
@ -100,10 +101,15 @@ static int dac_stm32_channel_setup(const struct device *dev,
return -ENOTSUP;
}
/* enable output buffer by default */
if (channel_cfg->buffered) {
output_buffer = LL_DAC_OUTPUT_BUFFER_ENABLE;
} else {
output_buffer = LL_DAC_OUTPUT_BUFFER_DISABLE;
}
LL_DAC_SetOutputBuffer(cfg->base,
table_channels[channel_cfg->channel_id - STM32_FIRST_CHANNEL],
LL_DAC_OUTPUT_BUFFER_ENABLE);
output_buffer);
LL_DAC_Enable(cfg->base,
table_channels[channel_cfg->channel_id - STM32_FIRST_CHANNEL]);

4
include/zephyr/drivers/dac.h
View file

@ -32,10 +32,14 @@ extern "C" {
* @param channel_id Channel identifier of the DAC that should be configured.
* @param resolution Desired resolution of the DAC (depends on device
* capabilities).
* @param buffered Enable output buffer for this channel. This is relevant for instance
* if the output is directly connected to the load, without an amplifier
* in between. The actual details on this are hardware dependent.
*/
struct dac_channel_cfg {
uint8_t channel_id;
uint8_t resolution;
bool buffered;
};
/**