8051 C code for PC Keyboard Interface - Wanted !

keyboard interfacing with 8051

Hi!

I am looking for a ready to use 'C' code (Keil51 V7.x preferably) to interface a standard PC AT keyboard to a standard 8051 micro.

I plan to connect the Keyboard CLK line to an Ext. Interrupt on the 8051. and sample the data line (on a standard port pin with a pull-up) on every interrupt. Any code to enable something like this would be perfect !!

I need 2 way communication - to toggle LEDS on the Keyboard.

Smokey

keyboard interface with 8051

Hi,
For your reference **broken link removed**

Regards
Jackson

keyboard interfacing in c

Thanks !

I have seen this app note from Philips before.

For this project, I am looking for a 'C' version (preferably written under Keil51 V7.x). I need to embedd the code as part of a larger firmware. I would like to use the PC-Keyboard Interface as a separate module - to be compiled conditionally with an `ifdef' statement.

Smokey

keyboard interface 8051

will this do ?
pm me for details

pc keyboard micro code

Many Thanks !!

The code seems 'just what the doctor ordered !'

Smokey ... over & Out !

pc keyboard interface to 8051

/********************************************************************
Keyboard to I2C. Read data under interrupt from an IBM keyboard
LPC config = 0xf8
********************************************************************/
#include <reg764.h>
#include <mydefs.h>

//----------------------------------- I2C routines
extern void init_I2C(void);
extern void slaveI2C(void);

extern uchar code kbtable[]; // Conversion Table

//----------------------- Globals
bit rx_flag;
uchar kdata, key_data;

//------------------------ Pin defs
sbit KB_DAT = P0^3;

/*--------------------------------------------------------------------------
*************************** MAIN PROGRAM *********************************
------------------------------------------------------------------------*/
main() {

WDRST = 0x1e; // reset watchdog
WDRST = 0xe1;
WDCON = 0x06;etc
WDRST = 0x1e;
WDRST = 0xe1;

EX1 = IT1 = 1; // external interrupt
init_I2C();
EA = 1;

/*******************************************************************/
while (1) {
WDRST = 0x1e; // feed WatchDog
WDRST = 0xe1;
//--------------------------------------
if (rx_flag == 1) {
static uchar KDA[3];
rx_flag = 0;
KDA[2] = KDA[1]; KDA[1] = KDA[0]; KDA[0] = kdata; // push

if (KDA[0] != 0xf0 && KDA[0] != 0xe0) { // if actual data
if (KDA[1] == 0xe0) { // prev was extended
KDA[0] |= 0x80; // convert data to extended
KDA[1] = KDA[2]; // pull back 1 stage
}
if (KDA[1] == 0xf0) { // prev was Break code
key_data = 0x00; //
slaveI2C(); // place in I2C buffer
// KDA[0]= KDA[1]= KDA[2]= 0x00;
}
else { // valid data handling
key_data = kbtable[KDA[0]];
slaveI2C(); // place in I2C buffer
// KDA[0]= KDA[1]= KDA[2]= 0x00;
} }
}
//---------------------------------------
} }

/********************************************************************
Keyboard clock interrupt
Receives Synchronous data 11 bits (Start,8,P,Stop)
********************************************************************/
ext1_isr() interrupt 2 {
uchar code mask[8] = {0x01,0x02,0x04,0x08,0x10,0x20,0x40,0x80};
static uchar kd; // the data Byte RXed
static uchar bit_cntr;
bit captBIT; // captured Data Bit

captBIT = KB_DAT;

if (bit_cntr == 0 && captBIT == 0) { // start BIT 0
bit_cntr = 1;
kd = 0; // Initialize data
}
else if (bit_cntr != 0 && bit_cntr < 9) { // 8 data bits
if (captBIT == 1) kd |= mask[bit_cntr-1]; // rotate
bit_cntr += 1;
}
else if (bit_cntr == 9) { // 9th bit (parity ?)
bit_cntr += 1;
}
else if (bit_cntr == 10 && captBIT == 1) { // stop bit
bit_cntr = 0;
kdata = kd;
rx_flag = 1;
}
else { // framing error
bit_cntr = 0;
}
}