Porting the PaPiRus HAT to the MDK

RE: Porting the PaPiRus HAT to the MDK

freund — Sun, 11 Sep 2016 23:40:01 GMT

Commit #8: “Shows cat and display image after clear”

epd.spi.h: 53: SPI_send_image() not used
Epd.c:202: epd->middle_scan=true: probably not needed as that’s the default value for the display firmware
Commenting: frame_data_repeat(). This code is needed but we couldn’t get the full pipeline of drawing to work according to spec. So our compromise was to feed inverted images to the draw_image function and skip the final inversion step.
Epd.c: has lots of dead commented code that’s not needed
Epd_spi.c:135 up_udelay(500): RPi has a more powerful CPU than our MuC. Since we spend more time sending the image data, we need to dial down the delay beetween bytes. We tuned this value to optimize performance but still get the send to work

RE: Porting the PaPiRus HAT to the MDK

freund — Sun, 11 Sep 2016 23:39:36 GMT

Commit #7: “Finally clear display routine works”.

Get SPI driver to compile and clear works.

MDK’s spi_send API should be able to support bi directional communication with a separate R and W buffer, but we couldn’t get it working, so in epd_spi.h:50, we made use of the MDK’s spi_send routine’s return value to support the R/W bi-directional communication.
Epd.c:41 needed to use mdk’s sleep functions included by mdk.h.
Epd.c:350: Delay_ms(1) is needed before every spi_send. It’s part of the PD protocol needed to initialize the control signal for SPI. This was found on p.15 of the PD spec. Under the “/cs” graph.
Stm32_spi.c: 1444: RPi’s epd_spi utility code did not clear the LSBFIRST bit. The MDK doesn’t support configuration of those clear bits, so we had no choice but to edit the MDK’s SPI code to NOT clear that bit.
Stm32_cpi.c: spi_portinitialize1() is dead code, should be ignored

RE: Porting the PaPiRus HAT to the MDK

freund — Sun, 11 Sep 2016 23:38:41 GMT

Commit #6: “Change the epd driver so now we are able to read cod version and it is 2”

Get epd to compile. Display version code can successfully read the HW, but nothing else works.

Uploading stm32_spi.c from MDK with no modification yet
Epd.c:322: Add code to read cog_id which returns a value of 2 (ie, the 2.0” display)
364: Support clearing display by breaking 2 byte send commands into 1 byte
339: Port “Check breakage” (of display HW) code by breaking 2 bytes into 1 byte send commands
Note that PD spec indicates that SPI_SELECT must be called before and after each Send
Epd_test.c:55 changing reset_pin direction to 1 is fixing our own bug
Spi.c was renamed to epd_spi.c. All ioctl from RPi was changed to SPI_SEND, for example:

if (-1 == ioctl(spi->fd, SPI_IOC_MESSAGE(1), transfer_buffer)) {ToSPI_SNDBLOCK(spi, buffer, length);This wasn’t captured by the github change diff because the file was renamed.

SPI_create for RPi uses fopen, was changed to spi_create which calls up_spiintialize(1) // SPI1
Set_spi_mode from rPi used icotls sets 3 values. Epd_spi.c accomplishes that on line 162 with:
- SPI_SETMODE(spi,in_mode);
- SPI_SETBITS(spi,8);
- SPI_SETFREQUENCY(spi,EPD_SPI_BPS);

RE: Porting the PaPiRus HAT to the MDK

freund — Sun, 11 Sep 2016 23:37:32 GMT

Commit #5: “Port the RaspberryPi driver to adapt to Mod HDK”.

Compile epd driver and test code.

map SPI structure to MDK library
Make use of remapped GPI r/w API’s
Update include path for epd.h to point to compile time arch/board folder
Nuttx C compiler doesn’t like variables to be declared inside of another statement such as a for loop. Similarly, the compiler got confused about re-using name of variable in nested scope on epd.c:739
Change RPi warn/error logging to MDK’s given dbg log function
Epd_test.c: strip down to 1 test case (clear screen)

RE: Porting the PaPiRus HAT to the MDK

freund — Sun, 11 Sep 2016 23:36:39 GMT

Commit #4: “Configure GPIO’s in the HDK and test it using RAW command and LEDs”.

Test code to verify that GPIO pins can be turned on and off using a Raw command

Gpio_test.h: original epd source
Mods.h: Add pin definitions.
Gpio_test.c: Remap gpio function names

RE: Porting the PaPiRus HAT to the MDK

freund — Sun, 11 Sep 2016 23:35:41 GMT

Commit #3: “Raspberri Pi epd driver drop” Dropping more original Pervasive Display source.

Makefile: No change from blinky
All headers and src are original epd source with original filenames

RE: Porting the PaPiRus HAT to the MDK

freund — Sun, 11 Sep 2016 23:33:39 GMT

Commit #2: Configuring the new project

Hdk-blinky.mnfs: Change name, remove unnecessary string
Defconfig:
- Enable SPI1 for communicating from Mod to E-Ink display
- Set VID=42 (Developer ID as per MDK instructions)
- Enable RAW, disable RAW_BLINKY (Note, we could have followed the template to create a RAW_EPD, but it’s not necessary)
- DISABLE_POSIX_TIMER: epd driver needs to use these timers from the MuC. Fixed a compilation problem in epd.c. Found to be necessary in later commit: d8088e2ff3b79e36a9cb441097ecab9aa320d792
Stm32_modsraw.c: Need to add a log statement so we can see our raw commands coming through from the phone to our kernel code.

RE: Porting the PaPiRus HAT to the MDK

freund — Sun, 11 Sep 2016 23:30:54 GMT

Commit #1: Creating a new MDK project

In this step, we'll clone the MDK's sample "Blinky" project into a new "epd" project (named after the RPi "epd.c" display driver for PaPiRus)

First copy the hdk-blinky.mnfs manifest and change the filename
Create an "epd" directory (named after the RPi "epd.c" display driver), and copied muc/blinky/Make.defs, setenv.sh, defconfig to this folder
Built the new "epd" project:

$ export PATH=$PATH:$BUILD_TOP/manifesto:$BUILD_TOP/bootrom-tools
$ cd $BUILD_TOP/nuttx/nuttx
# Needed if you previously built any other project, and are now ready to switch to our new epd project
$ make distclean
$ cd $BUILD_TOP/nuttx/nuttx/tools
# Copy files from epd directory to muc platform
$ ./configure.sh hdk/muc/epd

At this point, we should be ready to flash our new epd ("blinky") project as per the MDK flashing instructions.