Posted on May 17, 2011 at 09:40Hi,
I have 2 problems with my I2C communication. First of all, I am using a STR9 with a 24LC256 EEPROM.
1 - When the eeprom ack (9e clock) I saw a ''step'' on the scope. Normally, the eeprom should drive this line to 0 when ack. But the line is going to 2V and right after to 3V. It is like a bus contention.
2- The other problem is when I send a READ operation to the eeprom, the I2C does not generate a CLK. Normally if the ARM9 is the master, it should generate a clock, so that the EEPROM can answer. How can I do this ?
Here is the code (you can also get it with the attached file)
SCU_APBPeriphClockConfig(__GPIO2, ENABLE);
SCU_APBPeriphClockConfig(__I2C0,ENABLE);
SCU_APBPeriphReset(__GPIO2, DISABLE);
/**************************************** I2C EEPROM *************************************************/
GPIO_DeInit(GPIO2);
BSP_GPIOInit.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1; /* PIN_0 = I2C CLK, PIN_1 = I2C DATA */
BSP_GPIOInit.GPIO_Type = GPIO_Type_OpenCollector;
BSP_GPIOInit.GPIO_Direction = GPIO_PinOutput;
BSP_GPIOInit.GPIO_IPConnected = GPIO_IPConnected_Enable;
BSP_GPIOInit.GPIO_Alternate = GPIO_OutputAlt2;
GPIO_Init(GPIO2, &BSP_GPIOInit);
BSP_GPIOInit.GPIO_Pin = GPIO_Pin_2; /* PIN_2 = I2C WP */
BSP_GPIOInit.GPIO_Type = GPIO_Type_PushPull;
BSP_GPIOInit.GPIO_Direction = GPIO_PinOutput;
BSP_GPIOInit.GPIO_IPConnected = GPIO_IPConnected_Enable;
BSP_GPIOInit.GPIO_Alternate = GPIO_OutputAlt1;
GPIO_Init(GPIO2, &BSP_GPIOInit);
I2C_Cmd(I2C0,ENABLE);
GPIO_WriteBit(I2C_WP,Bit_RESET); /* disable WP bit for the EEPROM so we can write to it */
I2C_StructInit(&I2C_Struct);
I2C_DeInit(I2C0);
/* I2C0 Configuration */
I2C_Struct.I2C_GeneralCall = I2C_GeneralCall_Disable;
I2C_Struct.I2C_Ack = I2C_Ack_Enable;
I2C_Struct.I2C_CLKSpeed = 400000;
I2C_Struct.I2C_OwnAddress = 0X04;
I2C_Init(I2C0, &I2C_Struct);
I2C_AcknowledgeConfig(I2C0, DISABLE); /* no ACK for 24LC256 */
I2C_GenerateStart (I2C0, ENABLE);
EV(I2C0, EV5, ( EEPROM_ADDRESS & 0xFE ) ); // Write
EV(I2C0, EV6, 0X00 );
I2C_SendData(I2C0, 0x00); // Flash ADDRESS 0x0000
I2C_SendData(I2C0, 0x00); // Flash ADDRESS 0x0000
I2C_SendData(I2C0, 0xAA); // first data
I2C_SendData(I2C0, 0xBB); // second data to write
I2C_GenerateSTOP (I2C0, ENABLE);
/* --- begin reading at address 0x0000 -----*/
I2C_AcknowledgeConfig(I2C0, DISABLE); /* no ACK for 24LC256 */
I2C_GenerateStart (I2C0, ENABLE);
EV(I2C0, EV5, ( EEPROM_ADDRESS & 0xFE ) ); // Write
EV(I2C0, EV6, 0X00 );
I2C_SendData(I2C0, 0x00); // Flash ADDRESS 0x0000
I2C_SendData(I2C0, 0x00); // Flash ADDRESS 0x0000
I2C_AcknowledgeConfig(I2C0, ENABLE); /* no ACK for 24LC256 */
I2C_AcknowledgeConfig(I2C0, DISABLE); /* no ACK for 24LC256 */
I2C_GenerateStart (I2C0, ENABLE);
EV(I2C0, EV5, ( EEPROM_ADDRESS | 0x01 ) ); // READ
value = I2C_ReceiveData(I2C0); /* data 0xaa */
value = I2C_ReceiveData(I2C0); /* data 0xaa */
I2C_GenerateSTOP (I2C0, ENABLE);
