Important changes to forums and questions
All forums and questions are now archived. To start a new conversation or read the latest updates go to forums.mbed.com.
7 years, 7 months ago.
How does mbed handle I2C master functionality interally?
Not certain if this is the best place to seek advice for CMSIS issues, but I'm at my wits' end.
I'm using the second I2C device to communicate with a LM75-like temperature sensor.
I spent a long time not being able to get a response from the LM75 with the CMSIS libs until I used an mbed library from here
which allowed it to work perfectly.
Now that I know the address and I'm confident the actual sensor chip is functioning, I've been trying in earnest to access it using the standard CMSIS I2C library, but it just won't take off.
[Repository '/users/yoonghm/code/CMSIS/docs/c0b2dc6c836f/lpc17xx__i2c_8h.html' not found]
What I really need to know is what the mbed libraries are doing behind the scenes. So I can add any routines or tweak the configuration.
a good summary of my configuration in code
PINSEL_CFG_Type PinCfg; PinCfg.Funcnum = PINSEL_FUNC_2; PinCfg.OpenDrain = PINSEL_PINMODE_NORMAL; PinCfg.Pinmode = PINSEL_PINMODE_PULLUP; PinCfg.Portnum = PINSEL_PORT_0; //Set SDA PinCfg.Pinnum = PINSEL_PIN_10; //Refers to LPC1768 pin PINSEL_ConfigPin(&PinCfg); //Set SCL PinCfg.Pinnum = PINSEL_PIN_11; //Refers to LPC1768 pin PINSEL_ConfigPin(&PinCfg); //Set line frequency I2C_Init(i2c_device, 100000); I2C_Cmd(i2c_device, ENABLE); //Specify slave address and where to put the data i2c_cfg.sl_addr7bit = (LM75_SLAVE_ADDR_7) ; i2c_cfg.tx_data = tx_buffer; i2c_cfg.rx_data = rx_buffer; i2c_cfg.rx_length = (BUFFER_SIZE >> 1); //Queue up an initialise message tx_buffer = (LM75_SLAVE_ADDR_7 << 1); tx_buffer = 0x01; tx_buffer = 0x00; i2c_cfg.tx_length = 3; //Transfer function returns 0, i.e failure I2C_MasterTransferData(i2c_device, &i2c_cfg, I2C_TRANSFER_POLLING);
Thank you in advance for any help that can be offered.