Other Parts Discussed in Thread: PCF8574
Dear all,
I am using TIVA C Launchpad for this study. I am using I2C from PB2 and PB3 pins and connected through PCF8574. Pull up resistor at I2C pins are of 4.7kOhm. On IC PCF8574 I have connected cathode of LEDs. So when I drive pin P0, P1, P2, P3 to zero the LEDs should glow.
Now the problem is in my program if I write from 0 to 9 the four LEDs should glow. Till 9 LED glow perfectly but as I write A it starts with 1 again.
Below is the waveform coming:
and below is the code:
#include <stdbool.h>
#include <stdint.h>
#include "inc/hw_i2c.h"
#include "inc/hw_gpio.h"
#include "inc/hw_memmap.h"
#include "inc/hw_types.h"
#include "driverlib/gpio.h"
#include "driverlib/i2c.h"
#include "driverlib/pin_map.h"
#include "driverlib/sysctl.h"
#include "driverlib/uart.h"
#include "utils/uartstdio.h"
//*****************************************************************************
//! - I2C0 peripheral
//! - GPIO Port B peripheral (for I2C0 pins)
//! - I2C0SCL - PB2
//! - I2C0SDA - PB3
//
// Number of I2C data packets to send.
//
//*****************************************************************************
#define NUM_I2C_DATA 3
//*****************************************************************************
#define SLAVE_ADDRESS 0x20
void I2C_data(unsigned char data)
{
I2CMasterDataPut(I2C0_BASE,data);
I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_CONT);
while(I2CMasterBusy(I2C0_BASE)!=false)
{
;
}
SysCtlDelay(15000000);
I2CMasterDataPut(I2C0_BASE,data);
I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_CONT);
while(I2CMasterBusy(I2C0_BASE)!=false)
{
;
}
SysCtlDelay(15000000);
I2CMasterDataPut(I2C0_BASE,data);
I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_FINISH);
}
void I2C_String_Display(unsigned char *str)
{
while(*str)
{
I2C_data(*str);
str++;
}
return;
}
int main(void)
{
//
// Set the clocking to run directly from the external crystal/oscillator.
// TODO: The SYSCTL_XTAL_ value must be changed to match the value of the
// crystal on your board.
//
SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN |
SYSCTL_XTAL_16MHZ);
//
// The I2C0 peripheral must be enabled before use.
//
SysCtlPeripheralReset(SYSCTL_PERIPH_I2C0);
SysCtlPeripheralEnable(SYSCTL_PERIPH_I2C0);
//
// For this example I2C0 is used with PortB[3:2]. The actual port and
// pins used may be different on your part, consult the data sheet for
// more information. GPIO port B needs to be enabled so these pins can
// be used.
// TODO: change this to whichever GPIO port you are using.
//
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
//
// Configure the pin muxing for I2C0 functions on port B2 and B3.
// This step is not necessary if your part does not support pin muxing.
// TODO: change this to select the port/pin you are using.
//
GPIOPinConfigure(GPIO_PB2_I2C0SCL);
GPIOPinConfigure(GPIO_PB3_I2C0SDA);
//
// Select the I2C function for these pins. This function will also
// configure the GPIO pins pins for I2C operation, setting them to
// open-drain operation with weak pull-ups. Consult the data sheet
// to see which functions are allocated per pin.
// TODO: change this to select the port/pin you are using.
//
GPIOPinTypeI2CSCL(GPIO_PORTB_BASE, GPIO_PIN_2);
GPIOPinTypeI2C(GPIO_PORTB_BASE, GPIO_PIN_3);
//
// Enable loopback mode. Loopback mode is a built in feature that is
// useful for debugging I2C operations. It internally connects the I2C
// master and slave terminals, which effectively let's you send data as
// a master and receive data as a slave.
// NOTE: For external I2C operation you will need to use external pullups
// that are stronger than the internal pullups. Refer to the datasheet for
// more information.
//
HWREG(I2C0_BASE + I2C_O_MCR) = I2C_MCR_MFE ;
//
// Enable and initialize the I2C0 master module. Use the system clock for
// the I2C0 module. The last parameter sets the I2C data transfer rate.
// If false the data rate is set to 100kbps and if true the data rate will
// be set to 400kbps. For this example we will use a data rate of 100kbps.
//
I2CMasterInitExpClk(I2C0_BASE, SysCtlClockGet(), false);
// Tell the master module what address it will place on the bus when
// communicating with the slave. Set the address to SLAVE_ADDRESS
// (as set in the slave module). The receive parameter is set to false
// which indicates the I2C Master is initiating a writes to the slave. If
// true, that would indicate that the I2C Master is initiating reads from
// the slave.
//
I2CMasterSlaveAddrSet(I2C0_BASE, SLAVE_ADDRESS, false);
// Place the data to be sent in the data register
//
I2CMasterDataPut(I2C0_BASE,0x00);
// I2CMasterDataPut(I2C0_BASE,data);
//
// Initiate send of data from the master. Since the loopback
// mode is enabled, the master and slave units are connected
// allowing us to receive the same data that we sent out.
//
I2CMasterControl(I2C0_BASE, I2C_MASTER_CMD_BURST_SEND_START);
// Wait until master module is done transferring.
//
while(I2CMasterBusy(I2C0_BASE)!=false)
{
;
}
// SysCtlDelay(15000000);
I2C_String_Display("A");
}
Please let me know if there is something wrong in the sting defined. Because if I write through single command or without pointer it is working correctly. But with string pointer it does not.
