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Running Programs on Consolite

This document describes how to load programs onto the board and run them. Programs can either be loaded over a mini USB cable or via a micro SD card.

Consolite binaries are typically created using the provided assembler. The assembly code can either be written by hand, or you can write C-like code and compile it with the provided compiler. Binaries can be up to 64KiB in size. Once loaded into RAM, the processor begins executing at memory address 0x0000.

Loading over USB

If there is no micro SD card in the slot, Consolite will wait until it has received 64KiB of data over the UART interface has loaded the data into RAM. Data can be sent over USB by plugging the board into your computer and simply doing

cat PROGRAM_NAME /dev/zero > /dev/ttyACM0

from the terminal, where PROGRAM_NAME is the file you are loading and /dev/ttyACM0 is the name of the serial port for the board. You can figure out the name of the serial port by comparing the output of ls /dev before and after plugging the board into your computer. The /dev/zero is for padding the output with zeros in the likely case that the program you are loading is not exactly 64KiB.

The UART interface is only receiving at 19200 baud, since I had trouble getting it to send any faster - that means it will take about 34 seconds to load a program. Progress will be shown on the 7-segment display.

Loading from Micro SD Card

The preferred way of loading programs is from the micro SD card, since this takes only a fraction of a second and removes the reliance on an external computer when using Consolite. Additionally, you can have up to 256 programs stored on the SD card at a time.

The micro SD card I used was a class 4 8GB SDHC card - any SDHC card should work, and SDXC cards may work as well. Lower capacity cards (<= 2GB) won't work, as I didn't have access to any when writing the SD card controller so I couldn't add that functionality.

The micro SD card is used as a block device, so it doesn't need any file system. After plugging it in to your computer, you will want to unmount and possibly erase the existing file system. Unmounting should be enough however, since our direct writing of programs will probably destroy the file system anyway. To write a single program to the SD card, use:

dd if=PROGRAM_NAME of=/dev/mmcblk0

You may need to prefix this command with sudo. The output file, /dev/mmcblk0, might be different for your system, so you need to check the contents of ls /dev before and after plugging in the card.

To load multiple programs, you may want to create an image file before dding it to the SD card. First you need to pad each program to 64KiB, then concatenate them all together. Once the programs have been concatenated, the image can be written to the SD card. Suppose we have two files, program1 with size 512 bytes and program2 with size 1024 bytes:

# Pad files with 65536 - SIZE bytes
dd if=/dev/zero bs=1 count=65024 >> program1
dd if=/dev/zero bs=1 count=64512 >> program2
# Concatenate to form image
cat program1 program2 > image
# Write image to SD card, replacing /dev/mmcblk0 with your device's name
dd if=image of=/dev/mmcblk0

The reason the files need to be padded to a length of 64KiB is because, to find program N, Consolite loads the 64KiB program starting at byte offset N * 64KiB. The switches on the MimasV2 board act as an 8-bit binary number determining which program to load. If all the switches are in the 0 position when booting up Consolite, the 0th program will be loaded; if the switches are in the 00000001 position when booting, the 1st program will be loaded, etc. This allows you to have 256 different programs on the SD card ready to execute.

If you want to write a single program to a certain offset on the card, you can also do (where N is program index):

dd bs=65536 seek=N if=PROGRAM_NAME of=/dev/mmcblk0

This can be useful if you want to write a single program to the SD card without modifying the existing programs.