With a Nitrom 68HC908QY4 and a Hitachi LM052L LC Display I built a little
terminal.
The terminal is equipped with a RS232 connector and a debug port, that
works with the Motorola User Monitor. I didnīt solderd a level shifter
on the board, because I use my little pod, on the controller page or use
it directly on a controller. Because the terminal only has to receive characters,
I wrote a littele interrupt driven RS232 receive routine. I utilize the
KBD interrupt on PTA0 and call the GetbBte ROM routine to receive the character.
The ISR looks like this.
KbdIsr:
pshh ;save
H-reg
sei ;Disable
Interrupts
mov #%00000010,KBIER ;disable KB-Int
bclr PTA0,PTA ;initialize
PTA0 for serial comms
jsr GetByte ;call
GetByte at adress $2D6b
sta data ;store
the received character in RAM
mov #%00000100,KBSCR ;Clear Pending KBD interrupts
mov #%00000001,KBIER ;enable Keyboard interrupts
cli ;enable
ints
pulh ;get
H-reg back
rti
You can find schematics here. lcdschem.gif The software is here lcdterme.asm. It would fit into the 1.5 kB Flash of the 68HC908QY1 or 68HC908QY2 too,
but I had the 4 kB Version lying around so I used them.
Another display project is Zwobots Display. This project is programmed n C and uses a hardware SCI.
