ESP32 SPI MASTER NODMA EXAMPLE Save

Non DMA version of the spi_master driver

Based on esp-idf spi_master driver, modified by LoBo [https://github.com/loboris] 06/2017

The example uses wear leveling FAT file system and the latest esp-idf commit has to be used (5. May 2017 or later)

Main features

• Transfers data to SPI device in direct mode, not using DMA
• All configuration options (bus, device, transaction) are the same as in spi_master driver
• Transfers uses the semaphore (taken in select function & given in deselect function) to protect the transfer
• Number of the devices attached to the bus which uses hardware CS can be 3 (NO_CS)
• Additional devices which uses software CS can be attached to the bus, up to NO_DEV
• spi_bus_initialize & spi_bus_remove functions are removed, spi bus is initialized/removed in spi_nodma_bus_add_device/spi_nodma_bus_remove_device when needed
• spi_nodma_bus_add_device function has added parameter bus_config and automatically initializes spi bus device if not already initialized
• spi_nodma_bus_remove_device automatically removes spi bus device if no other devices are attached to it.
• Devices can have individual bus_configs, so different mosi, miso, sck pins can be configured for each device. Reconfiguring the bus is done automaticaly in spi_nodma_device_select function
• spi_nodma_device_select & spi_nodma_device_deselect functions handles devices configuration changes and software CS
• Some helper functions are added (get_speed, set_speed, ...)
• All structures are available in header file for easy creation of user low level spi functions. See tftfunc.c source for examples.
• Transimt and receive lenghts are limited only by available memory

Main driver's function is spi_nodma_transfer_data()

• TRANSMIT 8-bit data to spi device from trans->tx_buffer or trans->tx_data (trans->lenght/8 bytes) and RECEIVE data to trans->rx_buffer or trans->rx_data (trans->rx_length/8 bytes)
• Lengths must be 8-bit multiples! (for now)
• If trans->rx_buffer is NULL or trans->rx_length is 0, only transmits data
• If trans->tx_buffer is NULL or trans->length is 0, only receives data
• If the device is in duplex mode (SPI_DEVICE_HALFDUPLEX flag not set), data are transmitted and received simultaneously.
• If the device is in half duplex mode (SPI_DEVICE_HALFDUPLEX flag is set), data are received after transmission
• address, command and dummy bits are transmitted before data phase if set in device's configuration and if 'trans->length' and 'trans->rx_length' are not both 0
• If configured, devices pre_cb callback is called before and post_cb after the transmission
• If device was not previously selected, it will be selected before transmission and deselected after transmission.

Complete function decsriptions are available in the header file spi_master_nodma.h

You can place spi_master_nodma.c in <esp-idf_path>/components/driver directory and spi_master_nodma.h in <esp-idf_path>/components/driver/include/driver directory

In that case replace #include "spi_master_nodma.h" with #include "driver/spi_master_nodma.h" in spi_master_nodma.c

Example: SPI Display driver

TFT display driver features

• TFT library with many drawing functions and fonts is included.
• Full support for ILI9341 & ILI9488 based TFT modules in 4-wire SPI mode.
• 18-bit (RGB) color mode (default or 16-bit backed RGB565 color mode (only on ILI9341)
• DMA transfer mode on some functions to improve speed
• Grayscale mode can be selected
• Graphics functions: drawpixel, line, linebyangle, rect, roundrect, circle, ellipse, triangle, arc, poly, star ... All shapes can be filled or not. Drawing can be limitid to clipping window.
• Fonts: fixed width an proportional; 7 fonts embeded, unlimited number of fonts from file, 7-segment vector font with variable width/height. Proportional fonts can be used in fixed width mode.
• String write function: on x,y possition, center, left/right/top/bottom justify. Transparent or opaque writing, optional wrapping. Writting can be limitid to clipping window.
• Images: jpeg, bmp bitmap images.
• Touch screen supported (with XPT2046 controllers)
• Read from display memory supported

To run the example, attach ILI9341 or ILI9488 based display module to ESP32. Default pins used are:

• mosi: 23
• miso: 19
• sck: 18
• CS: 5 (display CS)
• DC: 26 (display DC)
• TCS: 25 (touch screen CS)

If you have ILI9488, set tft_disp_type = DISP_TYPE_ILI9488 in app_MAIN() in spi_master_demo.c

If you have ILI9341, set tft_disp_type = DISP_TYPE_ILI9341 in app_MAIN() in spi_master_demo.c

If you have ILI9341, set COLOR_BITS = 24 or COLOR_BITS = 16 in app_MAIN() in spi_master_demo.c

If you want to use different pins, change them in tftfunc.h

if you want to use the touch screen functions, set #define USE_TOUCH 1 in tftfunc.h

Using make menuconfig select tick rate 1000 ( → Component config → FreeRTOS → Tick rate (Hz) ) to get more accurate timings

• This example tests accessing ILI9341 or ILI9488 based display using spi_master_nodma driver
• Basics functions are executed first and timings at several spi clock speeds are printed.
• Four different JPG images are shown on screen to demonstrate jpeg decoding and scaling
• One BMP image is shown on screen to demonstrate bmp decoding
• Text and graphics are drawn on screen to demonstrate some drawing functions and text/fonts functionality
• Full color mode and grayscale mode are alternated on every pass
• On first 4 passes timings are printed for different operating modes
• If Touch screen is available, reading the touch coordinates (non calibrated) is also demonstrated. Keep the display touched until the info is printed
  • Raw coordinates are returned during the first phase (test).
  • Calibrated coordinates are returned while Text demo is displayed.

18-bit color mode

Jpeg decoding

Grayscale mode

Jpeg decoding

Example output:

I (1695) cpu_start: Pro cpu start user code
I (1748) cpu_start: Starting scheduler on PRO CPU.
I (1751) [SPI_FS]: Mounting FAT filesystem
E (1753) [SPI_FS]: FATFS mounted
E (1756) [SPI_FS]: JPG image found on file system

===================================
spi_master_nodma demo, LoBo 05/2017
===================================

SPI: display device added to spi bus
SPI: attached display device, speed=8000000
SPI: bus uses native pins: true
SPI: display init...
OK
-------------
 Disp clock =  8.00 MHz (requested:  8.00)
      Lines =  1396  ms (320 lines of 480 pixels)
 Read check      OK, line 218
     Pixels =  4151  ms (480x320)
        Cls =   475  ms (480x320)
-------------
-------------
 Disp clock = 10.00 MHz (requested: 10.00)
      Lines =  1395  ms (320 lines of 480 pixels)
 Read check      OK, line 293
     Pixels =  3572  ms (480x320)
        Cls =   382  ms (480x320)
-------------
-------------
 Disp clock = 16.00 MHz (requested: 16.00)
      Lines =  1394  ms (320 lines of 480 pixels)
 Read check      OK, line 300
     Pixels =  2718  ms (480x320)
        Cls =   244  ms (480x320)
-------------
### MAX READ SPI CLOCK set to 16.00 MHz ###
-------------
 Disp clock = 26.67 MHz (requested: 30.00)
      Lines =  1393  ms (320 lines of 480 pixels)
 Read check     Err, on line 232 at 17 (Read clock = 30.00 MHz)
     Pixels =  2131  ms (480x320)
        Cls =   152  ms (480x320)
-------------
-------------
 Disp clock = 40.00 MHz (requested: 40.00)
      Lines =  1392  ms (320 lines of 480 pixels)
 Read check      OK, line 163 (Read clock = 16.00 MHz)
     Pixels =  1835  ms (480x320)
        Cls =   106  ms (480x320)
-------------

Graphics demo started
---------------------

         DMA mode: OFF
   GRAYSCALE mode: OFF

Clear screen time: 226 ms
Display line time: 720 us
  JPG Decode time: 411 ms
Decode JPG (file): 411 ms
  BMP Decode time: 768 ms

         DMA mode: ON
   GRAYSCALE mode: OFF

Clear screen time: 106 ms
Display line time: 341 us
  JPG Decode time: 211 ms
Decode JPG (file): 211 ms
  BMP Decode time: 768 ms

         DMA mode: OFF
   GRAYSCALE mode: ON

Clear screen time: 453 ms
Display line time: 1586 us
  JPG Decode time: 742 ms
Decode JPG (file): 742 ms
  BMP Decode time: 1103 ms

         DMA mode: ON
   GRAYSCALE mode: ON

Clear screen time: 106 ms
Display line time: 958 us
  JPG Decode time: 557 ms
Decode JPG (file): 557 ms
  BMP Decode time: 1103 ms