The supported board list:
- SAMD21 Xplained Pro
- SAMR21 Xplained Pro
- SAML21 Xplained Pro
- SAML22 Xplained Pro
- SAMDA1 Xplained Pro
- SAMC21 Xplained Pro
- SAMHA1G16A Xplained Pro
In this use case, the I2C will used and set up as follows:
- Master mode
- 100KHz operation speed
- Not operational in standby
- 10000 packet timeout value
- 65535 unknown bus state timeout value
Prerequisites
The device must be connected to an I2C slave.
Setup
Code
The following must be added to the user application:
- A sample buffer to send, number of entries to send and address of slave:
#define DATA_LENGTH 10
static uint8_t buffer[DATA_LENGTH] = {
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09,
};
#define SLAVE_ADDRESS 0x12
Number of times to try to send packet if it fails:
- Globally accessible module structure:
- Function for setting up the module:
static void configure_i2c_master(void)
{
config_i2c_master.buffer_timeout = 10000;
#if SAMR30
config_i2c_master.pinmux_pad0 = CONF_MASTER_SDA_PINMUX;
config_i2c_master.pinmux_pad1 = CONF_MASTER_SCK_PINMUX;
#endif
i2c_master_init(&i2c_master_instance, CONF_I2C_MASTER_MODULE, &config_i2c_master);
}
- Globally accessible DMA module structure:
- Globally transfer done flag:
static volatile bool transfer_is_done = false;
- Globally accessible DMA transfer descriptor:
DmacDescriptor example_descriptor SECTION_DMAC_DESCRIPTOR;
- Function for transfer done callback:
static void transfer_done(
struct dma_resource*
const resource )
{
transfer_is_done = true;
}
- Function for setting up the DMA resource:
static void configure_dma_resource(
struct dma_resource *resource)
{
config.peripheral_trigger = CONF_I2C_DMA_TRIGGER;
}
- Function for setting up the DMA transfer descriptor:
static void setup_dma_descriptor(DmacDescriptor *descriptor)
{
descriptor_config.dst_increment_enable = false;
descriptor_config.block_transfer_count = DATA_LENGTH;
descriptor_config.source_address = (uint32_t)buffer + DATA_LENGTH;
descriptor_config.destination_address =
(uint32_t)(&i2c_master_instance.hw->I2CM.DATA.reg);
}
- Add to user application
main()
: configure_i2c_master();
configure_dma_resource(&example_resource);
setup_dma_descriptor(&example_descriptor);
Workflow
- Configure and enable module:
- Create and initialize configuration structure.
- Change settings in the configuration.
config_i2c_master.buffer_timeout = 10000;
#if SAMR30
config_i2c_master.pinmux_pad0 = CONF_MASTER_SDA_PINMUX;
config_i2c_master.pinmux_pad1 = CONF_MASTER_SCK_PINMUX;
#endif
- Initialize the module with the set configurations.
i2c_master_init(&i2c_master_instance, CONF_I2C_MASTER_MODULE, &config_i2c_master);
- Enable the module.
- Configure DMA
- Create a DMA resource configuration structure, which can be filled out to adjust the configuration of a single DMA transfer.
- Initialize the DMA resource configuration struct with the module's default values.
- Note
- This should always be performed before using the configuration struct to ensure that all values are initialized to known default settings.
- Set extra configurations for the DMA resource. It is using peripheral trigger. SERCOM TX trigger causes a transaction transfer in this example.
config.peripheral_trigger = CONF_I2C_DMA_TRIGGER;
- Allocate a DMA resource with the configurations.
- Create a DMA transfer descriptor configuration structure, which can be filled out to adjust the configuration of a single DMA transfer.
- Initialize the DMA transfer descriptor configuration struct with the module's default values.
- Note
- This should always be performed before using the configuration struct to ensure that all values are initialized to known default settings.
- Set the specific parameters for a DMA transfer with transfer size, source address, and destination address.
descriptor_config.dst_increment_enable = false;
descriptor_config.block_transfer_count = DATA_LENGTH;
descriptor_config.source_address = (uint32_t)buffer + DATA_LENGTH;
descriptor_config.destination_address =
(uint32_t)(&i2c_master_instance.hw->I2CM.DATA.reg);
- Create the DMA transfer descriptor.
Implementation
Code
Add to user application main()
:
i2c_master_dma_set_transfer(&i2c_master_instance, SLAVE_ADDRESS,
while (!transfer_is_done) {
}
while (true) {
}
Workflow
- Start the DMA transfer job.
- Set the auto address length and enable flag.
i2c_master_dma_set_transfer(&i2c_master_instance, SLAVE_ADDRESS,
- Waiting for transfer complete.
while (!transfer_is_done) {
}
- Enter an infinite loop once transfer complete.