Posted on February 22, 2013 at 14:56
Can you halping me understand where i'm wrong?
Thank's and sorry for my english.
#i2c-ack-issue
Hi everyone, first of all i've to tell you that i'm new with I2C bus.
I'm using I2C1 on STM32F103 ARM to communicate with an I2C eeprom (24LC256). I can see both SCL and SDA on my scope but it seems there is a problem with the ACK at the ninth clock. I've made the same test with a lux sensor MAX44009 and i can't be able to see any ACK at all. The testing function i use is:void
STM32_I2C_test(
void
)
{
uint8_t I2C_address;
uint32_t I2C_speed;
GPIO_InitTypeDef GPIO_InitStructure;
I2C_InitTypeDef I2C_InitStructure;
I2C_address = 0xA0;
//
//address = 0x94; //
I2C_speed = 1000;
// 1000Hz
/*enable I2C*/
I2C_Cmd(I2C1,ENABLE);
/* I2C1 clock enable */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C1, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);
/* I2C1 SDA and SCL configuration */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_OD;
GPIO_Init(GPIOB, &GPIO_InitStructure);
//SCL is pin06 and SDA is pin 07 for I2C1
/* I2C1 configuration */
I2C_InitStructure.I2C_Mode = I2C_Mode_SMBusHost;
I2C_InitStructure.I2C_DutyCycle = I2C_DutyCycle_2;
I2C_InitStructure.I2C_OwnAddress1 = 0x00;
I2C_InitStructure.I2C_Ack = I2C_Ack_Enable;
I2C_InitStructure.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit;
I2C_InitStructure.I2C_ClockSpeed = I2C_speed ;
I2C_Init(I2C1, &I2C_InitStructure);
//
/* check start bit flag */
while
(I2C_GetFlagStatus(I2C1, I2C_FLAG_BUSY));
/* initiate start sequence */
I2C_GenerateSTART(I2C1,ENABLE);
while
(!I2C_GetFlagStatus(I2C1, I2C_FLAG_SB));
/*send write command to chip*/
I2C_SendData(I2C1,I2C_address);
//I2C_Send7bitAddress(I2C1, address, I2C_Direction_Transmitter);
/*check master is now in Tx mode*/
while
(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED));
/*mode register address*/
I2C_SendData(I2C1, 0x02);
/*wait for byte send to complete*/
while
(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTED));
/*clear bits*/
I2C_SendData(I2C1, 0x00);
/*wait for byte send to complete*/
while
(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTED));
/*generate stop*/
I2C_GenerateSTOP(I2C1, ENABLE);
/*stop bit flag*/
while
(I2C_GetFlagStatus(I2C1, I2C_FLAG_STOPF));
}
Posted on October 31, 2014 at 07:37
The blue line is the SCL and the cyan the SDA. You see at the 9de clockpuls a ''half'' SDA signal. Have somebody an idea, what I can do? Thanks, Jan.
Hi,
I've also problems with the I2C-bus. I tested with the original dirvers of ST on the mcbstm32f400 eval kit of Keil. Also tried it on our pcb with a stm32f427 micro. We see the seem problem. At the 9de bit after the address, eeprom has to give an ack. But we get an ''half'' signal. The ST micro tried to pull-up and the eeprom to pull-down. When I tested it with ''handclocking'' in the code, it's okay. That means that the bus and address is correct. When i put an strange address for the eeprom, you see that the ack is 100% high. Thats okay, becauce there is no ic with that address. It looks like that the micro don't expect an ack. But bit 10 of CR1 is high, the reg-settings: I2C startup REG CR1 0x0401 CR2 0x002a CCR 0x01a4 TRISE 0x002b OAR1 0x4001 ** ST1 0x0000 ST2 0x0000 The blue line is the SCL and the cyan the SDA. You see at the 9de clockpuls a ''half'' SDA signal. Have somebody an idea, what I can do? Thanks, Jan.
