ADC extension for ESP32 (#1927)

* added adc extension

* add adc_number, for adc2

components/modules/Kconfig

@@ -47,6 +47,13 @@ depends on LUA_BUILTIN_DEBUG
 endmenu
 
 
+config LUA_MODULE_ADC
+  bool "ADC module"
+  default "n"
+  help
+      Includes the adc module. This module provides access to the
+      adc1 hardware.
+
 config LUA_MODULE_BIT
   bool "Bit module"
   default "n"

components/modules/adc.c

@@ -0,0 +1,77 @@
+// Module for interfacing with adc hardware
+
+#include "module.h"
+#include "lauxlib.h"
+#include "platform.h"
+
+
+// Lua: config( adc_id, bits )
+static int adc_set_width( lua_State *L )
+{
+  int adc_id = luaL_checkinteger( L, 1 );
+  MOD_CHECK_ID( adc, adc_id );
+  int bits = luaL_checkinteger( L, 2 );
+
+  if (!platform_adc_set_width( adc_id, bits ))
+    luaL_error( L, "adc_set_width failed" );
+
+  return 0;
+}
+
+// Lua: setup( adc_id, channel, atten )
+static int adc_setup( lua_State *L )
+{
+  int adc_id = luaL_checkinteger( L, 1 );
+  MOD_CHECK_ID( adc, adc_id );
+  int channel = luaL_checkinteger( L, 2 );
+  if (!platform_adc_channel_exists( adc_id, channel ))
+    luaL_error( L, "channel %d does not exist in ADC%d", ( unsigned )channel, ( unsigned )adc_id );
+
+  int atten = luaL_checkinteger( L, 3 );  
+
+  if (!platform_adc_setup( adc_id, channel, atten ))
+    luaL_error( L, "adc_setup failed" );
+
+  return 0;
+}
+
+// Lua: read( adc_id, channel )
+static int adc_read( lua_State *L )
+{
+  int adc_id = luaL_checkinteger( L, 1 );
+  MOD_CHECK_ID( adc, adc_id );
+  int channel = luaL_checkinteger( L, 2 );
+  if (!platform_adc_channel_exists( adc_id, channel ))
+    luaL_error( L, "channel %d does not exist in ADC%d", ( unsigned )channel, ( unsigned )adc_id );
+
+  int sample = platform_adc_read( adc_id, channel );
+  if (sample == -1)
+    luaL_error( L, "adc_read failed" );
+  lua_pushinteger( L, ( lua_Integer ) sample );
+  return 1;
+}
+
+// Lua: read_hall_sensor( )
+static int read_hall_sensor( lua_State *L )
+{
+  int sample = platform_adc_read_hall_sensor( );
+  lua_pushinteger( L, ( lua_Integer ) sample );
+  return 1;
+}
+
+// Module function map
+static const LUA_REG_TYPE adc_map[] =
+{
+  { LSTRKEY( "setwidth" ),       LFUNCVAL( adc_set_width ) },
+  { LSTRKEY( "setup" ),       LFUNCVAL( adc_setup ) },
+  { LSTRKEY( "read" ),        LFUNCVAL( adc_read ) },
+  { LSTRKEY( "read_hall_sensor" ),        LFUNCVAL( read_hall_sensor ) },
+  { LSTRKEY( "ATTEN_0db" ),   LNUMVAL( PLATFORM_ADC_ATTEN_0db ) },
+  { LSTRKEY( "ATTEN_2_5db" ), LNUMVAL( PLATFORM_ADC_ATTEN_2_5db ) },
+  { LSTRKEY( "ATTEN_6db" ),   LNUMVAL( PLATFORM_ADC_ATTEN_6db ) },
+  { LSTRKEY( "ATTEN_11db" ),  LNUMVAL( PLATFORM_ADC_ATTEN_11db ) },
+  { LSTRKEY( "ADC1" ),  LNUMVAL( 1 ) },
+  { LNILKEY, LNILVAL }
+};
+
+NODEMCU_MODULE(ADC, "adc", adc_map, NULL);

components/platform/include/platform.h

@@ -87,6 +87,20 @@ uint8_t platform_sigma_delta_close( uint8_t channel );
 uint8_t platform_sigma_delta_set_prescale( uint8_t channel, uint8_t prescale );
 uint8_t platform_sigma_delta_set_duty( uint8_t channel, int8_t duty );
 
+// *****************************************************************************
+// ADC
+int platform_adc_exists( uint8_t adc );
+int platform_adc_channel_exists( uint8_t adc, uint8_t channel );
+uint8_t platform_adc_set_width( uint8_t adc, int bits );
+uint8_t platform_adc_setup( uint8_t adc, uint8_t channel, uint8_t attn );
+int platform_adc_read( uint8_t adc, uint8_t channel );
+int platform_adc_read_hall_sensor( );
+enum {
+    PLATFORM_ADC_ATTEN_0db   = 0,
+    PLATFORM_ADC_ATTEN_2_5db = 1,
+    PLATFORM_ADC_ATTEN_6db   = 2,
+    PLATFORM_ADC_ATTEN_11db  = 3,
+};
 
 // *****************************************************************************
 // I2C platform interface

components/platform/platform.c

@@ -1,6 +1,7 @@
 #include "platform.h"
 #include "driver/console.h"
 #include "driver/sigmadelta.h"
+#include "driver/adc.h"
 #include <stdio.h>
 
 int platform_init (void)
@@ -152,7 +153,42 @@ uint8_t IRAM_ATTR platform_sigma_delta_set_duty( uint8_t channel, int8_t duty )
 {
   return ESP_OK == sigmadelta_set_duty( channel, duty ) ? 1 : 0;
 }
+// *****************************************************************************
+// ADC
 
+int platform_adc_exists( uint8_t adc ) { return adc < 2 && adc > 0; }
+
+int platform_adc_channel_exists( uint8_t adc, uint8_t channel ) {
+  return (adc == 1 && (channel >= 0 && channel < 8));
+}
+
+uint8_t platform_adc_set_width( uint8_t adc, int bits ) {
+  bits = bits - 9;
+  if (bits < ADC_WIDTH_9Bit || bits > ADC_WIDTH_12Bit)
+    return 0;
+  if (ESP_OK != adc1_config_width( bits ))
+    return 0;
+
+  return 1;
+}
+
+uint8_t platform_adc_setup( uint8_t adc, uint8_t channel, uint8_t atten ) {
+  if (adc == 1 && ESP_OK != adc1_config_channel_atten( channel, atten ))
+    return 0;
+
+  return 1;
+}
+
+int platform_adc_read( uint8_t adc, uint8_t channel ) {
+  int value = -1;
+  if (adc == 1) value = adc1_get_voltage( channel );
+  return value;
+}
+
+int platform_adc_read_hall_sensor( ) {
+  int value = hall_sensor_read( );
+  return value;
+}
 // *****************************************************************************
 // I2C platform interface
 

docs/en/modules/adc.md

@@ -0,0 +1,78 @@
+# ADC Module
+| Since  | Origin / Contributor  | Maintainer  | Source  |
+| :----- | :-------------------- | :---------- | :------ |
+| 2017-04-22 | | | [adc.c](../../../components/modules/bthci.c)|
+
+The ADC module provides access to the in-built ADC1.
+
+On the ESP32 there are two ADC. ADC1 has 8 channels, while ADC2 has 10 channels. Currently, only ADC1 is supported.
+
+## adc.setwidth()
+
+The configuration is in effect for all channels of ADC1
+
+#### Syntax
+`adc.setwidth(adc_number, bits)`
+
+#### Parameters
+- `adc_number` Only `adc.ADC1` now
+- `bits` One of `9`/`10`/`11`/`12`.
+
+#### Returns
+nil
+
+
+## adc.setup()
+
+Configuration ADC1 capture attenuation of channels
+
+#### Syntax
+`adc.setup(adc_number, channel, atten)`
+
+#### Parameters
+- `adc_number` Only `adc.ADC1` now
+- `channel`  When using `adc.ADC1`: `0` to `7`. 0: GPIO36, 1: GPIO37, 2: GPIO38, 3: GPIO39, 4: GPIO32, 5: GPIO33, 6: GPIO34, 7: GPIO35
+- `atten` One of following constants
+  - `adc.ATTEN_0db`    The input voltage of ADC will be reduced to about 1/1    (1.1V when VDD_A=3.3V)
+  - `adc.ATTEN_2_5db`  The input voltage of ADC will be reduced to about 1/1.34 (1.5V when VDD_A=3.3V)
+  - `adc.ATTEN_6db`    The input voltage of ADC will be reduced to about 1/2    (2.2V when VDD_A=3.3V)
+  - `adc.ATTEN_11db`   The input voltage of ADC will be reduced to about 1/3.6  (3.9V when VDD_A=3.3V,  maximum voltage is limited by VDD_A)
+
+#### Returns
+nil
+
+
+## adc.read()
+
+Samples the ADC. You should to call `setwidth()` before `read()`.
+
+#### Syntax
+`adc.read(adc_number, channel)`
+
+#### Parameters
+- `adc_number` Only `adc.ADC1` now
+- `channel` 0 to 7 for adc.ADC1
+
+#### Returns
+the sampled value (number)
+
+#### Example
+```lua
+val = adc.read(adc.ADC1, 0)
+```
+
+## adc.read_hall_sensor()
+
+Read Hall sensor (GPIO36, GPIO39). We recommend using 12-bits width on ADC1.
+
+#### Syntax
+`adc.read_hall_sensor()`
+
+#### Returns
+the sampled value (number)
+
+#### Example
+```lua
+val = adc.read_hall_sensor()
+```
+

mkdocs.yml

@@ -31,6 +31,7 @@ pages:
         - Extension Developer FAQ: 'en/extn-developer-faq.md'
     - Support: 'en/support.md'
     - Modules:
+        - 'adc':         'en/modules/adc.md'
         - 'bit':         'en/modules/bit.md'
         - 'bthci':       'en/modules/bthci.md'
         - 'dht':         'en/modules/dht.md'