Posted on April 24, 2017 at 08:32
Hi,
I have a I2C setting problem on STM8L101, I am using the ST's ''STM8L10x_StdPeriph_Driver'' library and try to setup the I2C bus to run at standard mode 100KHz (with system clock of 2MHz) for reading a magnetic sensor. Unfortunately, it seems the I2C clock simply does not start properly. However, if i slow down the I2C clock to 25KHz, the I2C bus becomes working normally and can get data from the magnetic sensor correctly.
Below is the program code that I used to configure the I2C interface of STM8L101:
====================================================
//Initialization of Peripheral and CPU clock
CLK_PeripheralClockConfig(CLK_Peripheral_I2C, ENABLE); //Activation of I2C_CTR clockCLK_MasterPrescalerConfig(CLK_MasterPrescaler_HSIDiv8); // System clock (fMaster clock) is 2MHz
// Setup I2C pin => PC0 = SDA, PC1 = SCL (Both pin has external 4.7KOhm pull-up resistor) GPIO_SetBits(MAIN_SCL_MAG_GPIO_PORT, MAIN_SCL_MAG_GPIO_PIN); // set HIGH GPIO_SetBits(MAIN_SDA_MAG_GPIO_PORT, MAIN_SDA_MAG_GPIO_PIN); GPIO_Init(GPIOC, MAIN_SDA_MAG_GPIO_PIN & MAIN_SCL_MAG_GPIO_PIN, GPIO_Mode_Out_OD_HiZ_Fast);
//Initialization of the integrated I2C peripheral
I2C_Cmd(ENABLE); //Activation of I2C peripheral I2C_DeInit(); //Initialization the I2C peripheral registers to their default reset values. I2C_Init(100000, 0xA0, I2C_DutyCycle_2,I2C_Ack_Enable,I2C_AcknowledgedAddress_7bit); // Initialization of I2C peripheral====================================================
If I use the below code (using 100KHz I2C speed), the I2C clock does NOT output:
I2C_Init(100000, 0xA0, I2C_DutyCycle_2,I2C_Ack_Enable,I2C_AcknowledgedAddress_7bit);
When I changed it to below code (using 25KHz I2C speed), the I2C clock can work correctly:
I2C_Init(25000, 0xA0, I2C_DutyCycle_2,I2C_Ack_Enable,I2C_AcknowledgedAddress_7bit);
Questions:
1) Do you know what would be the possible cause of this I2C setting problem?
2) How can I use the standard mode 100KHz and what registers setting shall be used?
Thanks!
