Hi all,

I work in the live event industry but I've started to use the mBed to code for my dissertation. I don't have any prior coding experience but I've got a lot of experience with electronics.

I'm trying to get my 16x2 Text LCD to display key presses from a PS2 keyboard, using some of the code from the Cookbook.

This is my code:

#include "mbed.h"
#include "TextLCD.h"                       
DigitalIn ps2clk(p21);
DigitalIn ps2din(p22);
TextLCD lcd(p24, p25, p26, p27, p28, p29, p30);        

static const unsigned char ps2KeyMap[] = {
//   0    1    2    3    4    5    6    7    8    9    A    B    C    D    E    F
' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', '`', ' ', // 00-0F
' ', ' ', ' ', ' ', ' ', 'Q', '1', ' ', ' ', ' ', 'Z', 'S', 'A', 'W', '2', ' ', // 10-1F
' ', 'C', 'X', 'D', 'E', '4', '3', ' ', ' ', ' ', 'V', 'F', 'T', 'R', '5', ' ', // 20-2F
' ', 'N', 'B', 'H', 'G', 'Y', '6', ' ', ' ', ' ', 'M', 'J', 'U', '7', '8', ' ', // 30-3F
' ', ',', 'K', 'I', 'O', '0', '9', ' ', ' ', '.', '/', 'L', ';', 'P', '-', ' ', // 40-4F
' ', ' ','\'', ' ', '[', '=', ' ', ' ', ' ', ' ', ' ', ']', ' ','\\', ' ', ' ', // 50-5F
' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', // 60-6F
' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', // 70-7F
' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', // 80-8F
' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', // 90-9F
' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', // A0-AF
' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', // B0-BF
' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', // C0-CF
' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', // D0-DF
' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', // E0-EF
' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', // F0-FF

};  

unsigned char ps2GetKey(void)
{
unsigned int buf;
int i;
buf = 0;
ps2clk = 0;                               // first error
ps2din.direction(0);                  // second error
ps2clk.direction(0);
for(i=0;i<11;i++) {
while(ps2clk);
while(!ps2clk);
buf = buf >> 1;
buf |= ps2din ? 512 : 0;
}
ps2clk.direction(1);
buf &= 0xFF;
return (unsigned char)buf;
}

int main(void)
{
printf("\n\rPS2 Keyboard:");
while(1) {
unsigned char c;
skip_break:
c = ps2GetKey();
if(c == 0xF0) {
c = ps2GetKey();
goto skip_break;
}
lcd.printf("%c", ps2KeyMap[c]);
}
return 0;
}

And in the compiler output I get the following warnings:

1st - No operator "=" matches these operands

2nd Class mbed::DigitalIn has no member "direction"

Can anybody tell me where I'm going wrong please? Would really appreciate it.

Simon Pettitt

Just use:

PS2ASCII myKeyboard(21, 23);

Ok thanks Vlad, I'll give that a go now.

There s a PS2ASCII class now so it is much easyer to use./

Make sure you use:

#include "PS2Kbd.h"

To include the class in your bin.

Let me know if there is anything else you need.

Thanks so much Vlad. Here is my new code:

#include "mbed.h"
#include "PS2Kbd.h"
#include "TextLCD.h"
#include "PS2ASCII.h"
//----------------------//
TextLCD lcd(p24, p25, p26, p27, p28, p29, p30);
PS2ASCII myKeyboard(21, 22);
DigitalOut LED(LED1);
int main() {
lcd.cls();                                  //clear screen

while (1) {
unsigned char symbol = myKeyboard.getChar();
if (symbol == 0x1B) {                       //clear screen function
lcd.cls();
continue;
}
if (myKeyboard.E0flag() == true) {          //is the make code one or two bytes long?
lcd.printf(" E0 ");
lcd.printf("%c ", symbol);
continue;
}
lcd.printf("%c", symbol);
}
}

But the compiler output says "Cannot open source input file "LPC2300.h":no such file or directory." It has this 7 times, 4 times referencing the PS2Keyboard library and 3 times referencing the PS2ASCII library...however I can't seem to find this other header file to make it happy...

Thanks for your help

Try starting with a clean new program it seems like your class files are not there.

I will try to replicate your example when I get home.

Great, thanks a lot. I'll give that a go.

Hi SimonP, Vlad,

I just had a look at the cookbook example you are discussing, and noticed it was done by someone who obviously had the older beta module and library. It therefore needs a little work to get working, and can also take advantage of some of the library improvements.

So I imported it, and just did a version to bring it up to date. This updated test version can be found at:

• PS2 Keyboard Program

The main changes were to change the pin names from int to PinName, and to use the new DigitalInOut class to support the bi-directional pin requirement. And that is about it really.

As I haven't got it wired up, I've only compiled it to test the changes I made have no basic problems, so you might have to do some final changes. Anyway, importing this project is probably a good starting point to get something working.

Simon

Fantastic, I'll try that.

Thanks Simon.