hi,


First the high nibble is sent, using the following
XBYTE[0x0a000] = 0x28 | 0x0f0;
delay(micro-seconds)
Then the low nibble.
XBYTE[0x0a000] = 0x28 | 0x0f;


no it is not correct. In fact, you still send data via 8-bit bus. Just at first step you send data over upper 4 bits and then over lower ones. If you need to send data using only 4 bits then you need modify your program, something like:

XBYTE[0x0a000] = 0x28>>4; 
delay();
XBYTE[0x0a000] = 0x28;

The example above sends data over lower 4 bits of data bus. If your hardware does it via upper bits then:

XBYTE[0x0a000] = 0x28; 
delay();
XBYTE[0x0a000] = 0x28<<4;

Regards,
Oleg