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olikraus edited this page Jun 28, 2015 · 2 revisions

U8glib with LPC1114FN28 ARM Microcontroller

This page documents work and results making u8glib compatible with ARM microcontrollers.

Reference Board

I decided to build a small microcontroller board based on the NXP LPC1114FN28:

  • LPC1114FN28 (DIP28) Microcontroller
  • Simple USB to UART converter (lower left in the following picture)

otherpic/lpc1114_um230xb.jpg

The board as two buttons: Reset button at the upper right and the programming button at the lower edge of the board. The programming button connects pin PIO0_1 to GND when pressed. Otherwise a pull up resistor will apply 3.3V to the pin.

The LPC1114 will be put into UART programming mode:

  1. Press and hold the programming button
  2. Press and release the reset button

Tool Chain

The tool chain is derived from the gcc-arm-embedded project https://launchpad.net/gcc-arm-embedded/. I will use "gcc-arm-none-eabi-4_7-2013q1" for Linux.

The following files are required to generate a .hex file for the target controller LPC1114:

  1. GCC and related tools https://launchpad.net/gcc-arm-embedded/4.7/4.7-2013-q1-update/+download/gcc-arm-none-eabi-4_7-2013q1-20130313-linux.tar.bz2
  2. LPC11xx specific header files, located in AN10995/CMSISv1p30_LPC11xx/inc of the zip file from http://www.nxp.com/documents/application_note/AN10995.zip

The archive gcc-arm-none-eabi-4_7-2013q1-20130313-linux.tar.bz2 contains the important linker (ld) script for the Cortex-M0 architecture in the folder /share/gcc-arm-none-eabi/samples/ldscripts:

linux:~/src/arm/gcc-arm-none-eabi-4_7-2013q1/share/gcc-arm-none-eabi/samples/ldscripts$ ls -al
drwxr-xr-x 2 kraus kraus 4096 Nov 14  2012 .
drwxr-xr-x 5 kraus kraus 4096 Dez  6 18:06 ..
-rw-r--r-- 1 kraus kraus  384 Mai 30 13:03 mem.ld
-rw-r--r-- 1 kraus kraus 2779 Aug 23  2012 sections.ld
-rw-r--r-- 1 kraus kraus 2724 Aug 23  2012 sections-nokeep.ld

For a plain minimal project, only mem.ld and sections.ld are required (sections-nokeep.ld will not work with U8glib). mem.ld must be updated for the target controller. In this case:

/* LPC1114 */
MEMORY
{
  FLASH (rx) : ORIGIN = 0x0, LENGTH = 0x8000 /* 32K */
  RAM (rwx) : ORIGIN = 0x10000000, LENGTH = 0x1000 /* 4K */
}

I have combinded the two .ld files into a single file: ldscript.ld. A complete project is placed here: http://code.google.com/p/u8glib/source/browse/#hg%2Fsys%2Flpc11xx%2Fplain. The project is almost independent from the target controller. It contains:

  • Makefile
  • C-Code (main procedure)
  • ldscript

Flash Tool

lpc21isp from http://lpc21isp.sourceforge.net/ is a good flash tool also for the LPC1114. Commandline options are:

lpc21isp <hex file> <linux port> <baud rate> <clock speed in KHz>

Usually this will look like this:

lpc21isp my.hex /dev/ttyUSB0 38400 12000

Remember to put the device into UART programming mode for this command (see above). After download of the hex code, another reset will start the code.

Target Specific Code

LPC11xx specific geader files are located in AN10995/CMSISv1p30_LPC11xx/inc of the zip file http://www.nxp.com/documents/application_note/AN10995.zip.

Blink Example Code

There are tree different versions of the blink example code. The code should be portable across all ARM controllers except for the pin control, which is specific for the LPC11xx.

  • Blink with "for" loop: blink
  • Blink with SysTick interrupt handler: systickblink
  • Blink with delay procedure (based on SysTick value): delayblink

External Links

http://vilaca.eu/lpc1114/

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