Pick-by-light LCD evaluation

Simple pick LCD
	with back light

Backlight on for the LM3S102 evaluation board

Pick-by-light Luminary board with LCD

The Luminary LM3S101 was advertised as a US$1 32-bit micro. With more memory than the previous 8-bit Atmel AVR 8515, it included JTAG debug, and was a lot cheaper. A huge difference was programming in C instead of assembler, with a source-level debugger and single-step capability. The internal registers, memory and peripherals were visible from the debugger interface—critical as nothing can be read external to the core with a logic analyzer or scope.

The Luminary Micro evaluation board was developed with IAR and included their JTAG debugger. The IAR stand-alone JTAG probe was more than the complete evaluation board, and with only five or so JTAG lines, we would cut a few tracks if more serious evaluation needed to be done with an external PCB. The LM3S102 on the board was almost identical to the LM3S101. We programmed the device to exercise the I/O, see how they mapped the internal bit memory and tested serial communications via the RS-232 port. To test the theory of being able to use the built-in JTAG, we removed the LM3S102 and replaced it with the LM3S101 that would be used in the targets for the “pick-by-light” displays.

The four files that might be useful are the main.c (21kBytes), drv_hd44780.c (34kBytes), nodeSerial.c (22kBytes) and manuf.h (1kBytes).

The LCD display was compatible to the standard Hitachi controller and connected up in 4-bit mode. The LCD code was based on the original supplied by IAR, but modified to work with a real-time tick interrupt. The code was borrowed from my 68000 work some twenty years before that—software if reasonably written can survive a generation or two of hardware. The serial interface messaging was started on the evaluation platform over a RS-232 port, but was later modified to work with RS-485.