Code writhe method

1

When we open new sketch in arduino, there are two pre defined functions available.

void setup() {}
and 
void loop() {}

where setup runs only one time.
how can I write such function in C, with platform IO

2

Just do one call of setup() and then call loop() within in infinite loop?

3

Ok,
I have few more doubts, Pl. explain,

can I define boolian type variable?
How can I use GPIO as 8 bit port ?

4

How to load a variable with hex OR binery value?

5

It seems you have problems about many programming basics in C/C++.

Thus I can only suggest free courses like https://www.udemy.com/course/free-learn-c-tutorial-beginners/ and Learn C++ - Free Interactive C++ Tutorial and https://www.youtube.com/watch?v=vLnPwxZdW4Y.

Instead of asking here and having to wait for an answer, please always google your questions first. The answer is pretty much always the first result.

C++ has the builtin type bool, so you can just do bool myVariable = false;. For C, you have to #include <stdbool.h> and then you get the same type and values.

Without knowing what exact microcontroller you’re talking about I have no idea how to answer that. Usually, there is some “output data register” for a GPIO pin bank (that can have 8 or 16 pins or whatever), but every MCU is different. For an ATMega328P and related, one would use PORTD = 0x..; to achieve that. That technical manual of your MCU is your friend here.

In C/C++, you just load it with a 0x prefix for hex or 0b for binary.

#include <stdint.h>

void some_func() {
   uint16_t myVar1 = 0xABCD;
   uint8_t myVar2 = 0b00110001;
}

note that there are forums / answer-question boards like stackoverflow.com/ that help in these cases – however, you should always look if your question wasn’t answered there before.

6

Thanks maxgerhardt,

I forgot the syntex, I wrote “boolian” instead of “bool” , thatswhy compiler shows error.

I have 15 yrs experience of AVR MEga MCU, mostly I am using mega32, and programming in assembly in AVR Studio. So I am aware of PORT, At present I want to know
How can I use port in ESP32?

7

Tell me one thing,
In the “led blink” example, how they get 1ms tick?
where is its code?

8

That’s an interesting question an the answer to that should lie in the implementation esp-idf/components/freertos at master · espressif/esp-idf · GitHub for the FreeRTOS timer (which isn’t necessarily 1ms, it’s configurable), and the GPIO driver is in https://github.com/espressif/esp-idf/blob/master/components/driver/gpio.c.

These all user timers of probably the XTensa CPU and the registers of the microcontroller itself, which are documented in https://www.espressif.com/sites/default/files/documentation/esp32_technical_reference_manual_en.pdf

Have you made progress here? I’m kind of interested in compiling a bare-metal project which just has a startup file, linker file and a small amount of code with direct register access for timer and GPIO access…

9

Just as a little side project I’ve started GitHub - maxgerhardt/minimal-esp32-sdk: Implements a no-dependencies (e.g. to ESP-IDF or Arduino-ESP32) SDK for the ESP32. as a bare-metal firmware project. No frameworks used, just header files and direct register access. It already runs a printf() loop and watchdog reset logic pretty nicely, and one can experiment with other peripherals (GPIO, timers, …) there too.

10

Can I debug in “single step” mode ? (only software, to check program flow)
how to protect code? is there any lock bit ? like avr controller ?

11

I know everything at chip level,(this is the reason I am working in assembly. each machine cycle is under my control). but problem is here, I dont know , how to write these stuff in C.
I also seen udemy video (as you suggested) but still there is some confusion. In that videos, they only discuss about software, not hardware.
I even dont know, what is the use of “cmake” file.

This is a video, I made this machine. its hardware is built with AVR mega32, it works within 25 micron accuracy. I run stepper motor in realtime ,without missing a single step