81 lines
2.3 KiB
C
81 lines
2.3 KiB
C
// Module for HX711 load cell amplifier
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// https://learn.sparkfun.com/tutorials/load-cell-amplifier-hx711-breakout-hookup-guide
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#include "module.h"
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#include "lauxlib.h"
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#include "platform.h"
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#include "c_stdlib.h"
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#include "c_string.h"
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#include "user_interface.h"
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static uint8_t data_pin;
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static uint8_t clk_pin;
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/*Lua: hx711.init(clk_pin,data_pin)*/
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static int hx711_init(lua_State* L) {
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clk_pin = luaL_checkinteger(L,1);
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data_pin = luaL_checkinteger(L,2);
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MOD_CHECK_ID( gpio, clk_pin );
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MOD_CHECK_ID( gpio, data_pin );
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platform_gpio_mode(clk_pin, PLATFORM_GPIO_OUTPUT, PLATFORM_GPIO_FLOAT);
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platform_gpio_mode(data_pin, PLATFORM_GPIO_INPUT, PLATFORM_GPIO_FLOAT);
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platform_gpio_write(clk_pin,1);//put chip to sleep.
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return 0;
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}
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#define HX711_MAX_WAIT 1000000
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/*will only read chA@128gain*/
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/*Lua: result = hx711.read()*/
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static int ICACHE_FLASH_ATTR hx711_read(lua_State* L) {
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uint32_t i;
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int32_t data = 0;
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//TODO: double check init has happened first.
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//wakeup hx711
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platform_gpio_write(clk_pin,0);
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//wait for data ready. or time out.
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//TODO: set pin inturrupt and come back to it. This may take up to 1/10 sec
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// or maybe just make an async version too and have both available.
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system_soft_wdt_feed(); //clear WDT... this may take a while.
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for (i = 0; i<HX711_MAX_WAIT && platform_gpio_read(data_pin)==1;i++){
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asm ("nop");
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}
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//Handle timeout error
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if (i>=HX711_MAX_WAIT) {
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return luaL_error( L, "ADC timeout!", ( unsigned )0 );
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}
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for (i = 0; i<24 ; i++){ //clock in the 24 bits
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platform_gpio_write(clk_pin,1);
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platform_gpio_write(clk_pin,0);
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data = data<<1;
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if (platform_gpio_read(data_pin)==1) {
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data = i==0 ? -1 : data|1; //signextend the first bit
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}
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}
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//add 25th clock pulse to prevent protocol error (probably not needed
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// since we'll go to sleep immediately after and reset on wakeup.)
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platform_gpio_write(clk_pin,1);
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platform_gpio_write(clk_pin,0);
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//sleep
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platform_gpio_write(clk_pin,1);
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lua_pushinteger( L, data );
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return 1;
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}
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// Module function map
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static const LUA_REG_TYPE hx711_map[] = {
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{ LSTRKEY( "init" ), LFUNCVAL( hx711_init )},
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{ LSTRKEY( "read" ), LFUNCVAL( hx711_read )},
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{ LNILKEY, LNILVAL}
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};
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int luaopen_hx711(lua_State *L) {
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// TODO: Make sure that the GPIO system is initialized
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return 0;
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}
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NODEMCU_MODULE(HX711, "hx711", hx711_map, luaopen_hx711);
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