FSM-55
Intro[edit]
Having fun with LED matrices!
Getting Started[edit]
You have to clone the repository with the FSM-55 firmware first:
git clone --branch cortex-m0-support git://git.gniibe.org/chopstx/chopstx.git
Second step is to install and configure a cross-compiler for the ARM Cortex-m0:
After configuring the cross-compiling environment, can compile the firmware by:
- Change to directory where we have the code examples:
example-fsm-55/
- Create a symbolic link to the FSM-55 board:
ln -s ../board/board-fsm-55.h board.h
- Compile the firmware:
make
Now, we are ready to upload the firmware to the board, but first we need to connect the board to the JTAG programmer.
Connecting your board[edit]
To program the board, we need to use a programmer with support to the SWD protocol. The most common tool is the proprietary device from ST-Electronics, ST-Link v.2. We are not very happy with it, since it has a proprietary firmware. Tentatively, you could try to use a Bus Pirate, which is supposed to support SWD.
Usually, you just need two wires to connect your STM32: clock and data lines, but, for the FSM-55 we need the 'reset' line as well. So, here is the pinout:
Creating your message[edit]
The fun of this exercise is to create your own message and convert it to a C program.
The program is organized in three threads:
- LED thread (dynamic LED control)
- Button thread (watchdog)
- Application thread (text screen control)
The user does not need to change the low-level threads (LED and Button), only the Application thread. The data flows from Application -> (some sort of) Video RAM -> LED control
Messages are encoded in a 5 x 5 grid of LEDs. The 'led' thread loops through each column of 5x5 grid.
----- ----- ----- ----- -----
Each LED is addressed as such:
- 0x00 * 0x00 * 0x00 * 0x00 * 0x00 * 0x00 - - * * * * - - - * * * - - - - * * - - - - - *
In other to present the message "Happy Hacking!" only the characters we use (including exclamation point and space) are described:
{ 3, 0 }, /* SPACE */ { 4, DATA55V (0x1f, 0x04, 0x04, 0x1f, 0x00) }, /* H */ { 3, DATA55V (0x17, 0x15, 0x0f, 0x00, 0x00) }, /* A */ { 4, DATA55V (0x1f, 0x14, 0x14, 0x08, 0x00) }, /* P */ { 4, DATA55V (0x19, 0x05, 0x05, 0x1e, 0x00) }, /* Y */ { 4, DATA55V (0x0e, 0x11, 0x11, 0x0a, 0x00) }, /* C */ { 4, DATA55V (0x1f, 0x04, 0x0c, 0x13, 0x00) }, /* K */ { 3, DATA55V (0x11, 0x1f, 0x11, 0x00, 0x00) }, /* I */ { 4, DATA55V (0x1f, 0x08, 0x06, 0x1f, 0x00) }, /* N */ { 4, DATA55V (0x0e, 0x11, 0x15, 0x07, 0x00) }, /* G */ { 2, DATA55V (0x1d, 0x1c, 0x00, 0x00, 0x00) }, /* ! */
The message is represented as a string:
static uint8_t hh[] = { CHAR_H, CHAR_A, CHAR_P, CHAR_P, CHAR_Y, CHAR_SPC, CHAR_H, CHAR_A, CHAR_C, CHAR_K, CHAR_I, CHAR_N, CHAR_G, CHAR_EXC, CHAR_SPC, CHAR_SPC, CHAR_SPC, };
Uploading your code[edit]
Authors[edit]
Gniibe is the author of the FSM-55. Unixjazz and Gniibe are the authors of this tutorial. It is released under CC-BY-SA-2.1 JP. Feel free to redistribute it and modify it for your needs.