Hello,
I am using a nRF DK (nRF52832 - PCA10040 - SDK 15) to communicate with a custom electronic device developed by my own company (which integrates an 1-Wire slave).
The communication protocol is 1-Wire so I use a Single-Channel 1-Wire Master called DS2482-100 from Maxim Integrated, it is an I²C-to-1-Wire bridge device (datasheet here).
------------- ------------- ------------------
| | | | | |
| nRF DK | ----- I²C/TWI ----- | DS2482 | ----- 1Wire ----- | 1Wire Slave |
| | | | | |
------------- ------------- ------------------
I rewrote the code from Maxim Integrated (see this) by using the twi nrf driver.
The I²C original functions were replaced by nrf_drv_twi functions.
int I2C_write(unsigned char data, int expect_ack) --------> nrf_drv_twi_tx(&m_twi, TWI_address, twi_data_write, sizeof(twi_data_write), false)
unsigned char I2C_read(int ack) --------> nrf_drv_twi_rx(&m_twi, TWI_address, &m_twi_data_read, sizeof(m_twi_data_read))
Everything works fine when I want to do a ROM research or to write a byte (1-Wire protocol).
My issue comes from the data read. It seems like there is a bit shift somewhere. I have three 1-Wire commands for testing with my custom device.
1) Turn on LED of the custom device (it works, so writing is ok)
Expected result : 4 bytes (hexadecimal) 0000AAAA
Current result : 4 bytes (hexadecimal) 00005455
2) Turn off LED of the custom device (it works, so writing is ok)
Expected result : 4 bytes (hexadecimal) 0000AAAA
Current result : 4 bytes (hexadecimal) 00005455
3) Information request (no action from the custom device)
Expected result : 5 bytes (hexadecimal) 0000110108
Current result : 5 bytes (hexadecimal) 0000220210
I don't know where the problem comes from because the byte writing and the ROM research work.
Here is my code for OWReadByte function ://--------------------------------------------------------------------------
// Send 8 bits of read communication to the 1-Wire Net and return the
// result 8 bits read from the 1-Wire Net.
//
// Returns: 8 bits read from 1-Wire Net
//
unsigned char OWReadByte(void)
{
// 1-Wire Read Bytes (Case C)
// S AD,0 [A] 1WRB [A] Sr AD,1 [A] [Status] A [Status] A\
// \--------/
// Repeat until 1WB bit has changed to 0
// Sr AD,0 [A] SRP [A] E1 [A] Sr AD,1 [A] DD A\ P
//
// [] indicates from slave
// DD data read
ret_code_t err_code;
uint8_t twi_config_write[] = {CMD_1WRB};
err_code = nrf_drv_twi_tx(&m_twi, TWI_address, twi_config_write, sizeof(twi_config_write), true);
APP_ERROR_CHECK(err_code);
int poll_count = 0;
//m_twi_data_read = NULL;
do
{
err_code = nrf_drv_twi_rx(&m_twi, TWI_address, &m_twi_data_read, sizeof(m_twi_data_read));
APP_ERROR_CHECK(err_code);
//__LOG(LOG_SRC_APP, LOG_LEVEL_INFO, "[OWWait_1WB_0()] do while : m_twi_data_read 0x%.2x\n", m_twi_data_read);
}
while ((m_twi_data_read & STATUS_1WB) && (poll_count++ < POLL_LIMIT));
__LOG(LOG_SRC_APP, LOG_LEVEL_INFO, "[OWWait_1WB_0()] apres do while : m_twi_data_read 0x%.2x\n", m_twi_data_read);
// check for failure due to poll limit reached
if (poll_count >= POLL_LIMIT)
{
__LOG(LOG_SRC_APP, LOG_LEVEL_INFO, "[OWWait_1WB_0()] Poll limit reached.\n");
DS2482_reset();
return FALSE;
}
uint8_t twi_data_write[] = {CMD_SRP, RGT_READ_D}; //Read Data Register
err_code = nrf_drv_twi_tx(&m_twi, TWI_address, twi_data_write, sizeof(twi_data_write), false);
APP_ERROR_CHECK(err_code);
err_code = nrf_drv_twi_rx(&m_twi, TWI_address, &m_twi_data_read, sizeof(m_twi_data_read));
APP_ERROR_CHECK(err_code);
return ((unsigned char) m_twi_data_read);
}
And the initialization ://--------------------------------------------------------------------------
// Perform a twi initialisation
//
void twi_init(void)
{
ret_code_t err_code;
const nrf_drv_twi_config_t twi_config = {
.scl = SCL_PIN,
.sda = SDA_PIN,
.frequency = NRF_DRV_TWI_FREQ_100K,
.interrupt_priority = APP_IRQ_PRIORITY_HIGH,
.clear_bus_init = false
};
err_code = nrf_drv_twi_init(&m_twi, &twi_config, NULL, NULL);
APP_ERROR_CHECK(err_code);
nrf_drv_twi_enable(&m_twi);
//DS2482 reset and config
DS2482_detect(DS2482_ADDR);
}
Thanks for your help,
Matthieu
