Obsolete IIC calls in the RPi build?

So if the GPU is “undocumented” and the datasheet is for code running on the ARM, what the is the point in putting the real addresses when they’re…inaccessible…?

They aren’t inaccessible. If you’re programming one of the DMA controllers then you need to give it GPU physical addresses.

Sorry to interupt – I got my code fully working:

// Demo code to access Flexel Data Aquisition Module
// from Raspberry Pi (first Revision) running RISC OS via BSC registers



//------------- Header files

#include <stdio.h>
#include <stdlib.h>
#include "kernel.h"
#include "swis.h"



//------------- Define start of BSC register addresses

#define BSC_physical 0x20205000

//------------- use 0x20804000 for a second revision board



//------------- Define read, write, cleansing and status values

#define BSC_C_I2CEN (1 << 15)
#define BSC_C_INTR (1 << 10)
#define BSC_C_INTT (1 << 9)
#define BSC_C_INTD (1 << 8)
#define BSC_C_ST (1 << 7)
#define BSC_C_CLEAR (1 << 4)
#define BSC_C_CLEAR_II (1 << 5)
#define BSC_C_READ 1

#define CLEAR_FIFO  BSC_C_CLEAR|BSC_C_CLEAR_II
#define START_READ  BSC_C_I2CEN|BSC_C_ST|BSC_C_CLEAR|BSC_C_READ
#define START_WRITE BSC_C_I2CEN|BSC_C_ST

#define BSC_S_CLKT (1 << 9)
#define BSC_S_ERR (1 << 8)
#define BSC_S_RXF (1 << 7)
#define BSC_S_TXE (1 << 6)
#define BSC_S_RXD (1 << 5)
#define BSC_S_TXD (1 << 4)
#define BSC_S_RXR (1 << 3)
#define BSC_S_TXW (1 << 2)
#define BSC_S_DONE (1 << 1)
#define BSC_S_TA 1

#define CLEAR_STATUS BSC_S_CLKT|BSC_S_ERR|BSC_S_DONE



//------------- Function declarations

unsigned int Memory_Map(unsigned int base);
void ByteWriteI2C(unsigned short int device_addr, unsigned char data_byte);
unsigned short int ByteReadI2C(unsigned short int device_addr);
void wait_i2c_done();
void init();
void EmptyFIFO();
void MultiByteWriteI2C(unsigned short int device_addr, unsigned short int length);
void MultiByteReadI2C(unsigned short int device_addr, unsigned short int length);


//------------- Set up pointers to mapped logical address

unsigned char FIFO_access[16]={0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
unsigned int BSC_logical;
unsigned int volatile * BSC_C;
unsigned int volatile * BSC_S;
unsigned int volatile * BSC_DLEN;
unsigned int volatile * BSC_A;
unsigned int volatile * BSC_FIFO;



void init()
{
printf("\ninitialising...\n");
BSC_logical = Memory_Map(BSC_physical);
BSC_C = (unsigned int *) (BSC_logical+0x0);
BSC_S = (unsigned int *) (BSC_logical+0x04);
BSC_DLEN = (unsigned int *) (BSC_logical+0x08);
BSC_A = (unsigned int *) (BSC_logical+0x0C);
BSC_FIFO = (unsigned int *) (BSC_logical+0x10);
*BSC_C=CLEAR_FIFO;
}



//------------- Map physical addresses to logical addresses

unsigned int Memory_Map(unsigned int base)
{
printf("mapping...");
_kernel_swi_regs r;
r.r[0] = (1 << 17) + 13;
r.r[1] = base;
r.r[2] = 1024;
_kernel_swi(OS_Memory, &r, &r);
return r.r[3];
}



//——————— Function to empty FIFO

void EmptyFIFO()
{
*BSC_C=CLEAR_FIFO;
}



//——————— Function to write one byte to I2C bus

void ByteWriteI2C(unsigned short int device_addr, unsigned char data_byte)
{
printf("\nchanging BSC register values...\n");
*BSC_C=CLEAR_FIFO;
*BSC_S = CLEAR_STATUS;
*BSC_A = device_addr;
*BSC_DLEN = 1;
*BSC_FIFO = data_byte;
printf("starting to write transaction...\n");
*BSC_C = START_WRITE;
wait_i2c_done();
}



//——————— Function to read one byte from I2C bus

unsigned short int ByteReadI2C(unsigned short int device_addr)
{
printf("\nchanging BSC register values to send bus address only...\n");
*BSC_C=CLEAR_FIFO;
*BSC_S = CLEAR_STATUS;
*BSC_A = device_addr;
*BSC_DLEN = 1;
printf("starting to write transaction...\n");
*BSC_C = START_WRITE;
wait_i2c_done();
printf("changing BSC register values to read...\n");
*BSC_S = CLEAR_STATUS;
*BSC_A = device_addr;
*BSC_DLEN = 1;
printf("starting to send transaction...\n");
*BSC_C = START_READ;
wait_i2c_done();
printf("reading one byte from FIFO...\n");
return *BSC_FIFO;
}



//——————— Function to write multiple bytes to I2C bus

void MultiByteWriteI2C(unsigned short int device_addr, unsigned short int length)
{
unsigned short int i=0;
printf("\nchanging BSC register values...\n");
*BSC_C=CLEAR_FIFO;
*BSC_S = CLEAR_STATUS;
*BSC_A = device_addr;
*BSC_DLEN = length;
while(i<length)
{
*BSC_FIFO=FIFO_access[i];
FIFO_access[i]=0;
i++;
}
printf("starting to write transaction...\n");
*BSC_C = START_WRITE;
wait_i2c_done();
}



//——————— Function to read Multiple bytes from I2C bus

void MultiByteReadI2C(unsigned short int device_addr, unsigned short int length)
{
unsigned short int i=0;
printf("\nchanging BSC register values to send bus address only...\n");
*BSC_C = CLEAR_FIFO;
*BSC_S = CLEAR_STATUS;
*BSC_A = device_addr;
*BSC_DLEN = 0;
printf("starting to write transaction...\n");
*BSC_C = START_WRITE;
wait_i2c_done();
printf("changing BSC register values to read...\n");
*BSC_S = CLEAR_STATUS;
*BSC_A = device_addr;
*BSC_DLEN = length;
printf("starting to send transaction...\n");
*BSC_C = START_READ;
wait_i2c_done();
printf("reading multiple bytes from FIFO...\n");
while(i<length)
{
FIFO_access[i]=*BSC_FIFO;
i++;
}
}



//------------- display I2C transaction status

void dump_bsc_status()
{
unsigned int s = *BSC_S;
printf("BSC0_S: ERR=%d  RXF=%d  TXE=%d  RXD=%d  TXD=%d  RXR=%d  TXW=%d  DONE=%d  TA=%d\n",
(s & BSC_S_ERR) != 0,
(s & BSC_S_RXF) != 0,
(s & BSC_S_TXE) != 0,
(s & BSC_S_RXD) != 0,
(s & BSC_S_TXD) != 0,
(s & BSC_S_RXR) != 0,
(s & BSC_S_TXW) != 0,
(s & BSC_S_DONE) != 0,
(s & BSC_S_TA) != 0 );
}



//------------- Function to wait for the I2C transaction to complete

void wait_i2c_done()
{
printf("status before completion - ");
dump_bsc_status();
printf("waiting for transaction to complete...\n");
unsigned short int timeout = 50;
unsigned short int i;
while((!((*BSC_S) & BSC_S_DONE)) && --timeout)
{
i=0;
while(i<5000)
{
i++;
}
}
if(timeout == 0)
printf("wait_i2c_done() timeout. Something went wrong.\n");
printf("status after completion - ");
dump_bsc_status();
}



//------------- Here we go...!

int main(int argc, char **argv)
{
// initialise
init();

// send characters to screen
ByteWriteI2C(0x48,48); //send '0' to lcd
ByteWriteI2C(0x48,49); //send '1' to lcd
ByteWriteI2C(0x48,50); //send '2' to lcd
ByteWriteI2C(0x48,51); //send '3' to lcd
ByteWriteI2C(0x48,52); //send '4' to lcd
ByteWriteI2C(0x48,53); //send '5' to lcd
ByteWriteI2C(0x48,54); //send '6' to lcd
ByteWriteI2C(0x48,55); //send '7' to lcd
ByteWriteI2C(0x48,56); //send '8' to lcd
ByteWriteI2C(0x48,57); //send '9' to lcd

// turn down LCD backlight
FIFO_access[0]=0xFE;
FIFO_access[1]=0x03;
FIFO_access[2]=0x10;
MultiByteWriteI2C(0x48,3);

//read and display time from Real Time Clock
FIFO_access[0]=0xFE;
FIFO_access[1]=0x2A;
MultiByteWriteI2C(0x48,2);
MultiByteReadI2C(0x48,3);
printf("\nTime: %d hours %d minutes %d seconds\n",FIFO_access[2],FIFO_access[1],FIFO_access[0]);
return 0;
}

Thanks again.