ESP8266 Community Forum

- Sat Mar 14, 2015 10:19 am #11960 Hi!

Is it possible to use TX2 (from second uart) from Lua Nodemcu or did somebody implemented successfully software, bitbang uart tx?

Thanks,
Patriko

- Sat Mar 14, 2015 11:38 am #11966 Ok, if it'll be useful for somebody, I implemented in C in nodemcu firmware, here is the code:

Code: Select all#include "lualib.h"
#include "lauxlib.h"
#include "platform.h"
#include "auxmods.h"
#include "lrotable.h"
#define Baudrate        2400
#define OneBitDelay     (1000000/Baudrate)
#define DataBitCount    8

static int ICACHE_FLASH_ATTR rgbw_write(lua_State* L) {
  const uint8_t pin = luaL_checkinteger(L, 1);
  size_t length;
  const char *buffer = luaL_checklstring(L, 2, &length);
  char c = *buffer;


  platform_gpio_mode(pin, PLATFORM_GPIO_OUTPUT, PLATFORM_GPIO_FLOAT);

  platform_gpio_write(pin, 0);
  os_intr_lock();

  os_delay_us(OneBitDelay);
  uint8_t mask = 0;

  unsigned char i = 0;
  for(i = 0; i < DataBitCount; i++)
  {
     if((c>>i)&0x01)
     {
        platform_gpio_write(pin, 1);
     }
     else
     {
        platform_gpio_write(pin, 0);
     }
       os_delay_us(OneBitDelay);
  }
  //stop bit
  platform_gpio_write(pin, 1);
  os_delay_us(OneBitDelay);
  os_intr_unlock();

  return 0;
}

#define MIN_OPT_LEVEL 2
#include "lrodefs.h"
const LUA_REG_TYPE rgbw_map[] =
{
  { LSTRKEY( "write" ), LFUNCVAL( rgbw_write )},
  { LNILKEY, LNILVAL}
};

LUALIB_API int luaopen_rgbw(lua_State *L) {
  LREGISTER(L, "rgbw", rgbw_map);
  return 1;
}

// ----------------------------------------------------------------------------



- Sat Mar 14, 2015 12:07 pm #11968 So just for me to learn
If I wanted to use this code? is it in NodeMCU?
Should I compile something for it?

How do I use c code, in nodemcu, can this code be compiled, and then added externally? so I can have the current NodeMcu and add to it?
Again, this is for knowing and understanding

- Tue Mar 17, 2015 11:31 am #12123 Hi,

you have to compile it with node mcu, just like ws2812 (it's based on it) and next you can use lua command (in this case rgbw.write(char) (I forgot to change the name to better reflect purpose, in my case it controls external RGBW controller).