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ESP Libraries

ESP Arduino standard SW stack

• https://github.com/esp8266/Arduino
• [[https://github.com/espressif/arduino-esp32
  • https://github.com/espressif/arduino-esp32/tree/master/variants

PlatformIO - Library management

lib_deps =
    bodmer/TFT_eSPI@^1.2.3
    https://github.com/stickbreaker/OneWire.git#v2.3.3-ESP32 

Where

• 1.2.3 - an exact version number. Use only this exact version
• ^1.2.3 - any compatible version (exact version for 1.x.x versions
• ~1.2.3 - any version with the same major and minor versions, and an equal or greater patch version
• >1.2.3 - any version greater than 1.2.3. >=, <, and <= are also possible
• >0.1.0,!=0.2.0,<0.3.0 - any version greater than 0.1.0, not equal to 0.2.0 and less than 0.3.0

ISR - interrupt service routines

MUTEX

PWM and Timers

Links

• https://lastminuteengineers.com/esp32-pwm-tutorial/
• https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/peripherals/ledc.html

PWM Channels

Now let us turn our attention to the concept of a channel. A channel represents a unique PWM output signal.
The ESP32 has 16 channels, which means it can generate 16 unique PWM waveforms. These channels are divided into two groups,
each containing 8 channels: 8 high-speed channels and 8 low-speed channels.

Within each group, there are 4 timers shared among 8 channels, which means that every two channels share the same timer. Since the timer determines the frequency, it’s important to understand that we cannot adjust the frequency of each channel independently within a pair. However, we can control the PWM duty cycle of each channel independently.

The ESP32 can generate a PWM signal with a frequency of up to 40 MHz, and the PWM resolution can be adjusted from 1 to 16 bits. But this doesn’t mean you can set a frequency of 40 MHz and a resolution of 16 bits at the same time. This is due to the fact that the maximum PWM frequency and resolution are both bound by the clock source.

PSRAM

• https://thingpulse.com/esp32-how-to-use-psram/
  • https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-guides/external-ram.html#esp32-rev-v1

When PSRAM not detected

• Check if boardXxxx.json contains : "extra_flags": "-DBOARD_HAS_PSRAM -mfix-esp32-psram-cache-issue"
• For deeper digging : build_flags = -DCORE_DEBUG_LEVEL=5
• then check serial COM output, ex. : [D][esp32-hal-psram.c:47] psramInit(): PSRAM enabled

        bool psramFound();
        void *ps_malloc(size_t size);
        void *ps_calloc(size_t n, size_t size);
        void *ps_realloc(void *ptr, size_t size);

ESP-NOW

• https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/network/esp_now.html
• https://randomnerdtutorials.com/esp32-esp-now-wi-fi-web-server/ ... Using ESP-NOW and Wi-Fi Simultaneously
• https://randomnerdtutorials.com/esp-now-esp32-arduino-ide/
  • https://randomnerdtutorials.com/esp32-web-server-sent-events-sse/
• https://github.com/yoursunny/WifiEspNow

DS18B20

• paulstoffregen/OneWire .. newest version 2.3.5 doesnot work for ESP32 due to two cores and bad timing of 1-Wire bus
• https://github.com/stickbreaker/OneWire .. patched vesion
• milesburton/DallasTemperature

Does not work with ESP32

• problem is OneWire library
• See :
  https://github.com/espressif/arduino-esp32/issues/1335 .. change timming values in delayMicroseconds(X)
  https://github.com/PaulStoffregen/OneWire/issues/57 .. changed library timming for ESP32
• Solutions :
  • use older version of paulstoffregen/OneWire @ 2.3.3
  • use https://github.com/stickbreaker/OneWire ... A modification of the Arduino OneWire library maintained by @PaulStoffregen. This modifications supports the ESP32 under the Arduino-esp32 Environment.

OTA - Over The Air (firmware update)

YouTube guides

• YouTube - Jan Penninkhof - Over-the-Air (OTA) ESP8266 programming using PlatformIO
• YouTube - Andreas Spiess - #32 Internet of Things with ESP8266 #4: Upload Programs Over the Air (OTA)
• YouTube - Andreas Spiess - #110 Complete OTA with a Reed Switch ?
• YouTube - Andreas Spiess - #157 Simple OTA Software Distribution for ESP8266 (IOTappStory.com)
• YouTube - Andreas Spiess - #225 How-to Manage your ESP32 and ESP8266 over the Air (IOTappstory.com)
• YouTube - Andreas Spiess - #332 ESP32 OTA tutorial with tricks (incl. OTA debugging)
• TelnetStream
  • Stream implementation over telnet for OTA debuging
  • jandrassy/TelnetStream @ ^1.2.1
  • ameer1234567890/TelnetStream2 @ ^1.0.0
• WiFiManager
  • WiFi Configuration manager with web configuration portal for ESP boards
  • tzapu/WiFiManager @ ^0.16.0

GxEPD - Libraries Comparison

• https://github.com/lewisxhe/GxEPD
• https://github.com/ZinggJM/GxEPD
• https://github.com/Xinyuan-LilyGO/T5-Ink-Screen-Series/ .. (./lib/GxEPD/src/)

GxEPD2 - Libraries Comparison

• https://github.com/ZinggJM/GxEPD2
• https://github.com/emxfer/GxEPD2 + DEPG0213BN

ULP - Ultra Low Power

YouTube guides

• https://www.youtube.com/watch?v=-QIcUTBB7Ww
• https://www.youtube.com/watch?v=n_A_8Y4xNx8
• EXTREME POWER SAVING (0µA) with Microcontroller External Wake Up: Latching Power Circuit

Sleep modes

BootMode

• https://github.com/espressif/esptool/wiki/ESP32-Boot-Mode-Selection#boot-mode-message

rst cause:2, boot mode:(X,Y)

• rst cause
  • 1 – normal boot after power-on
  • 2 – reboot by reset button/pin
  • 4 – reboot caused by watchdog timer
• X = three low bits of x are {MTDO=GPIO16, GPIO0, GPIO2}
  • 1 = uploadFLASH via Serial port {GPIO16,GPIO0,GPIO2} = {0,0,1}
  • 3 = running from FLASH {GPIO16,GPIO0,GPIO2} = (0,1,1)
  • 5 = boot spi mode from UART
  • 7 = boot spi mode from SPI
• Y =
  • 7 SDIO HighSpeed V2 IO Uart1 Booting
  • 6 SDIO LowSpeed V1 IO Uart1 Booting
  • 5 SDIO HighSpeed V1 IO Uart1 Booting
  • 4 SDIO LowSpeed V2 IO Uart1 Booting
  • 3 FLASH BOOT
  • 2 Jump Boot
  • 1 UART Boot
  • 0 Remapping

DEBUG LEVEL

• https://community.platformio.org/t/how-to-set-up-log-level-to-be-able-to-debug-the-esp32/8278

build_flags = -DCORE_DEBUG_LEVEL=ARDUHAL_LOG_LEVEL_DEBUG

    esp32-hal-log.h :
    #define ARDUHAL_LOG_LEVEL_NONE       (0)
    #define ARDUHAL_LOG_LEVEL_ERROR      (1)
    #define ARDUHAL_LOG_LEVEL_WARN       (2)
    #define ARDUHAL_LOG_LEVEL_INFO       (3)
    #define ARDUHAL_LOG_LEVEL_DEBUG      (4)
    #define ARDUHAL_LOG_LEVEL_VERBOSE    (5)

esptool

• https://github.com/espressif/esptool/
• https://blog.vyoralek.cz/iot/esp8266-a-esp32-zaloha-a-nahrani-noveho-firmware-pomoci-esptool/
• Install esptool :
  c:\> pip3 install esptool
c:\> pip3 install esptool --upgrade

Info

• (flash_id) :
  c:\TMP\> esptool.py --chip auto -p COM4 -b 115200 flash_id

            Manufacturer: 20
            Device: 4016
            Detected flash size: 4MB

• (read_mac) :
  c:\TMP\> esptool.py --chip auto -p COM4 -b 115200 read_mac

            MAC: 84:cc:a8:5e:59:c0

• (chip_id) :
  c:\TMP\> esptool.py --chip auto -p COM4 -b 115200 chip_id

            Warning: ESP32 has no Chip ID. Reading MAC instead.
            MAC: 84:cc:a8:5e:59:c0

• (read_flash_status) :
  c:\TMP\> esptool.py --chip auto -p COM4 -b 115200 read_flash_status

            Enabling default SPI flash mode... (--no-stub)
            Status value: 0x0000

Flashing

• Backup (read_flash) :
  c:\TMP\> esptool.py --chip esp32 -p COM4 -b 115200 read_flash 0x00000 0x400000 backup.img
• Erase (erase_flash) :
  c:\TMP\> esptool.py --chip esp32 -p COM4 -b 115200 erase_flash
• Write (write_flash) :
  c:\TMP\> esptool.py --chip esp32 -p COM4 -b 115200 write_flash 0x00000 backup.img

PATH of : esptool.py :

• C:\Users\XXXXXXXX\.platformio\packages\framework-arduinoespressif32\tools\ esptool.py
• C:\Users\XXXXXXXX\.platformio\packages\framework-arduinoespressif8266\tools\esptool\ esptool.py
• C:\Users\XXXXXXXX\.platformio\packages\tool-esptoolpy\ esptool.py

               [--chip {auto,esp8266,esp32,esp32s2,esp32s3beta2,esp32s3,esp32c3,esp32c6beta,esp32h2,esp8684}]
               [--port PORT] [-p PORT] 
               [--baud BAUD] [-b BAUD]

               [--before {default_reset,usb_reset,no_reset,no_reset_no_sync}]
               [--after {hard_reset,soft_reset,no_reset,no_reset_stub}]
               [--no-stub] [--trace] [--override-vddsdio [{1.8V,1.9V,OFF}]]
               [--connect-attempts CONNECT_ATTEMPTS]

               {load_ram, dump_mem, read_mem, write_mem, 
                write_flash, run, image_info, make_image, elf2image,
                read_mac, chip_id, flash_id, read_flash_status, write_flash_status, 
                read_flash, verify_flash, 
                erase_flash, erase_region, merge_bin, version, get_security_info}
               ...