I'm sending data to the UART of a philips lpc936, all communications are fine, but I want to start passing arguements into the data stream. All my arguements pass properly, what isn't happening is the hex nibbles are not being converted to ascii properly.

Now if I sent say:

uart_transmit('B'); //the SBUF shows 0x42 as it should

But if I use a variable that is assigned by a passed arguement, it just sends the regular hex without converting it. Now I know you can not have something like '7B' since that is an invalid ascii character. So what i've done is mask with F0 and 0F to get the byte broken into two nibbles. I want to convert the nibble data into ASCII.

The Keil help file says to use this:

int toascii (int c); 

so I try

unsigned char REG_H;
REG_H  = (reg  & 0xF0);
REG_H  = (toascii (REG_H));

But it basically ignores it. I have #include <ctype.h> on the UART.C page.

It compiles with no warnings or errors, but when I run the Keil debugger, it never converts correctly. Not sure what I'm doing wrong or why it won't convert. But if I do the ('B'), the UART simulates the proper ASCII character in the SBUF and send.....this is also validated in the hardware that i'm sending via RS232.

Any ideas what could be up? GRANTED: I have not tried to use the toascii on anything but the REG_H thus far, figuring if REG_H isn't converting, nothing else will. Trying to find the right answer and then I'll implement it for the rest of the REG, DAT variables.

Here is the function:

void RS232_Write(unsigned char reg, unsigned char dat0, unsigned char dat1)
{

unsigned char REG_H, REG_L, DAT1_H, DAT1_L, DAT2_H, DAT2_L, CHECKSUM_H,  CHECKSUM_L, CHECKSUM_T ;

REG_H  = (reg  & 0xF0);
REG_L  = (reg  & 0x0F );
DAT1_H = (dat0 & 0xF0 );
DAT1_L = (dat0 & 0x0F );
DAT2_H = (dat1 & 0xF0 );
DAT2_L = (dat1 & 0x0F );

CHECKSUM_T = (cam_header + cam_ID_H+ cam_ID_L + REG_H + REG_L + DAT1_H + DAT1_L + DAT2_H + DAT2_L);

CHECKSUM_H = (CHECKSUM_T & 0xF0);
CHECKSUM_L = (CHECKSUM_T & 0x0F);

//***********************************************************************
uart_init();
uart_transmit(cam_header); 	Wait(2); 	//header
uart_transmit(cam_ID_H); 	Wait(2); 	//ID H
uart_transmit(cam_ID_L); 	Wait(2); 	//ID L
uart_transmit('B');             Wait(2); <<<<<<<<WORKS AS IT SHOULD
uart_transmit(REG_L); 		Wait(2); 	//Register L
uart_transmit(DAT1_H); 		Wait(2);	//Data 1 H
uart_transmit(DAT1_L); 		Wait(2);	//Data 1 L
uart_transmit(DAT2_H); 		Wait(2);	//Data 2 H
uart_transmit(DAT2_L); 		Wait(2);	//Data 2 L
uart_transmit(CHECKSUM_H); 	Wait(2);	// Send calculated checksum 1
uart_transmit(CHECKSUM_L); 			// Send calculated checksum 2
//***********************************************************************
}

Hopefully its something simple? Does it HAVE to be an int for the toascii?? All my variables are unsigned chars to keep them as small as possible.

Thanks
Chris