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Everything you wanted to know about ESP32 but were too afraid to ask!

Pugwash · 2020-08-23T12:40:22Z

NO, NOT REALLY! But there is definitely something that users of ESP32s should at least know about, namely FreeRTOS and multitasking. The ESP32 costs about the same as a Nano, but where performance is concerned it is like comparing a Lamborghini to a Citroen Deux Chevaux. Here is some simple boilerplate code to get started (no bells and whistles here). #include "Arduino.h" //delete if using Arduino IDE // all #includes, #defines and global variables go here // NOTE: declare all global variables here as "volatiles" TaskHandle_t Task0; TaskHandle_t Task1; void loop0(void * parameter) { //declare local variables here for (;;) { // your sketch 1 code goes here } } void loop1(void * parameter) { //declare local variables here for (;;) { // your sketch 2 code goes here } } void setup() { Serial.begin(115200); Serial.println("Setup started."); xTaskCreatePinnedToCore( loop0, /* Function to implement the task */ "Task0", /* Name of the task */ 1000, /* Stack size in words */ NULL, /* Task input parameter */ 0, /* Priority of the task */ &Task0, /* Task handle. */ 1); /* Core where the task should run */ xTaskCreatePinnedToCore( loop1, /* Function to implement the task */ "Task1", /* Name of the task */ 1000, /* Stack size in words */ NULL, /* Task input parameter */ 0, /* Priority of the task */ &Task1, /* Task handle. */ 1); /* Core where the task should run */ Serial.println("Setup completed."); } void loop() { delay(0); //just for compilation } And here is a simple demo showing two sketches(tasks) running simultaneously, using the semaphore flag to invoke the second sketch(task). All that is required is one ESP32 and two LEDs attached to GPIO pins 25 and 27. #include "Arduino.h" TaskHandle_t Task0; TaskHandle_t Task1; SemaphoreHandle_t semaphore; #define LED0 27 #define LED1 25 void loop0(void * parameter) { int limit = 10; for (;;) { for(int n = 0; n < limit; n++){ if(n == 5){ xSemaphoreGive(semaphore); //set the semaphore flag } digitalWrite(LED0, HIGH); delay(1000); digitalWrite(LED0, LOW); delay(1000); } } } void loop1(void * parameter) { int limit = 5; for (;;) { xSemaphoreTake(semaphore, portMAX_DELAY); //wait for semaphore flag to be set for(int n = 0; n < limit; n++){ digitalWrite(LED1, HIGH); delay(1000); digitalWrite(LED1, LOW); delay(1000); } } } void setup() { Serial.begin(115200); Serial.println("Setup started."); pinMode(LED0, OUTPUT); pinMode(LED1, OUTPUT); semaphore = xSemaphoreCreateBinary(); xTaskCreatePinnedToCore( loop0, /* Function to implement the task */ "Task0", /* Name of the task */ 1000, /* Stack size in words */ NULL, /* Task input parameter */ 0, /* Priority of the task */ &Task0, /* Task handle. */ 1); /* Core where the task should run */ xTaskCreatePinnedToCore( loop1, /* Function to implement the task */ "Task1", /* Name of the task */ 1000, /* Stack size in words */ NULL, /* Task input parameter */ 0, /* Priority of the task */ &Task1, /* Task handle. */ 1); /* Core where the task should run */ Serial.println("Setup completed."); } void loop() { vTaskDelete(NULL); //helps with compiling } Have fun!! I have only skimmed the surface of FreeRTOS, maybe Dronebot could make an instructional video on this subject.

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ESP32 & ESP8266

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Markzagit

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2021-12-04 5:07 pm

What's also interesting is that my pins are opposite to the diagram. My pin 5 is actually where pin 35 is on the diagram.

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DroneBot Workshop

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2021-12-04 5:41 pm

@markzagit Can you post or link to the instructions that are telling you to jumper pin 5 please. I'm not sure if you are talking about physical pin 5 or GPIO pin 5.

Also, I'm questioning why you soldered the wire jumpers? Didn't you say it needed to be jumped for 10 seconds, then removed?

It would be a lot easier if you used a solderless breadboard, especially if you're unsure of the connections.

😎

Bill

"Never trust a computer you can’t throw out a window." — Steve Wozniak

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Markzagit

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2021-12-04 6:30 pm

@dronebot-workshop Hi, I included the instructions (in italics) on the previous page.

I soldered the wires to the board, then held the +/- to the battery (which I checked with a multimeter to make sure it was at 3.3-3.4V before connecting) for 10 seconds.

Sorry, I don't have a solderless breadboard.

Thanks again for your help.

This post was modified 3 years ago by Markzagit

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Markzagit

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2021-12-04 6:45 pm

Actually, this is more in line with mine:

WIFI_Kit_32_pinoutDiagram_V2.pdf

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Markzagit

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2021-12-04 9:22 pm

@dronebot-workshop OK, this reply slipped under the radar. I didn't see it before. so I've measured the 3.3 and indeed it is putting out 3.3V when connected to the USB. So just connect that to pin 5 (which is GPIO5 as well) and wait for about 10 seconds?

OK, I tried for 10 seconds, then 15. Nothing. Should I be holding down the reset button at the same time or anything? What about the RST pin? Should I try that?

This post was modified 3 years ago by Markzagit

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Markzagit

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