How to configure two I2C SERCOM on SAMD20E17?

Discussions around product based on ARM Cortex M0+ core.

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How to configure two I2C SERCOM on SAMD20E17?

Fri Jul 25, 2014 4:07 pm

I will use SAMD20E17 with two I2C SERCOMs (one in master mode and one in slave mode). Acc to Table 5-1: "PORT Function Multiplexing on page" of the SAMD20 datasheet, I understand that for SAMD20Exx (please correct me if I'm wrong):
PA16 is SERCOM1 (data)
PA17 is SERCOM1 (clk)
PA22 is SERCOM3 (data)
PA23 is SERCOM3 (clk).

First, I only implement SERCOM3; with the following configuration:

Code: Select all

void configure_i2c_master(void)
	/* Initialize config structure and software module. */
	struct i2c_master_config config_i2c_master;

	config_i2c_master.buffer_timeout = 1000;  // TEB: was 10000
     i2c_master_init(&i2c_master_instance, SERCOM3, &config_i2c_master);
This works fine, but when I try to send some data, the following happens:

Code: Select all

I call the:  i2c_master_write_packet_wait(...)
... which calls: _i2c_master_write_packet(...)
static enum status_code _i2c_master_write_packet(
		struct i2c_master_module *const module,
		struct i2c_master_packet *const packet)
	SercomI2cm *const i2c_module = &(module->hw->I2CM);

	/* Return value. */
	enum status_code tmp_status;
	uint16_t tmp_data_length = packet->data_length;


	/* Set address and direction bit. Will send start command on bus. */
	i2c_module->ADDR.reg = (packet->address << 1) | I2C_TRANSFER_WRITE;
The above statement causes a branch to the HardFault_Handler()

Prior to entering HardFault_Handler(), the datastructures contains the following:
i2c_module = 0x42001400

packet = 20000058
->address = 0x00000055
->data_lenght = 0x00000004
->data = 0x0cde4 <bq_buf_ctrl> "" (*data=0)
->ten_bit_adress = false
->high_speed = false
->hs_master_code = 0
->address = 0x00000055

Any clues ?

It seems like my pointers all have OK (?) values ?
Why this branch to HardFault_Handler() ?
Are there any configuration error for this SERCOM3?

I'll very much appreaciate assistance with this issue.

Best Regards Terje Bohler

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