add simga_delta module

components/modules/Kconfig

@@ -91,6 +91,13 @@ config LUA_MODULE_NODE
   help
       Includes the node module (recommended).
 
+config LUA_MODULE_SIGMADELTA
+  bool "Sigma-Delta module"
+  default "n"
+  help
+      Includes the sigma_delta module. This module provides access to the
+      sigma-delta hardware.
+
 config LUA_MODULE_STRUCT
   bool "Struct module"
   default "n"

components/modules/sigma_delta.c

@@ -0,0 +1,90 @@
+// Module for interfacing with sigma-delta hardware
+
+#include "module.h"
+#include "lauxlib.h"
+#include "platform.h"
+
+
+// Lua: setup( channel, pin )
+static int sigma_delta_setup( lua_State *L )
+{
+  int channel = luaL_checkinteger( L, 1 );
+  int pin = luaL_checkinteger( L, 2 );
+
+  MOD_CHECK_ID(sigma_delta, channel);
+
+  if (!platform_sigma_delta_setup( channel, pin ))
+    luaL_error( L, "command failed" );
+
+  return 0;
+}
+
+// Lua: close( channel )
+static int sigma_delta_close( lua_State *L )
+{
+  int channel = luaL_checkinteger( L, 1 );
+
+  MOD_CHECK_ID(sigma_delta, channel);
+
+  platform_sigma_delta_close( channel );
+
+  return 0;
+}
+
+#if 0
+// Lua: setpwmduty( channel, duty_cycle )
+static int sigma_delta_setpwmduty( lua_State *L )
+{
+  int channel = luaL_checkinteger( L, 1 );
+  int duty = luaL_checkinteger( L, 2 );
+
+  MOD_CHECK_ID(sigma_delta, channel);
+
+  if (!platform_sigma_delta_set_pwmduty( channel, duty ))
+    luaL_error( L, "command failed" );
+
+  return 0;
+}
+#endif
+
+// Lua: setprescale( channel, value )
+static int sigma_delta_setprescale( lua_State *L )
+{
+  int channel = luaL_checkinteger( L, 1 );
+  int prescale = luaL_checkinteger( L, 2 );
+
+  MOD_CHECK_ID(sigma_delta, channel);
+
+  if (!platform_sigma_delta_set_prescale( channel, prescale ))
+    luaL_error( L, "command failed" );
+
+  return 0;
+}
+
+// Lua: setduty( channel, value )
+static int sigma_delta_setduty( lua_State *L )
+{
+  int channel = luaL_checkinteger( L, 1 );
+  int duty = luaL_checkinteger( L, 2 );
+
+  MOD_CHECK_ID(sigma_delta, channel);
+
+  if (!platform_sigma_delta_set_duty( channel, duty ))
+    luaL_error( L, "command failed" );
+
+  return 0;
+}
+
+
+// Module function map
+static const LUA_REG_TYPE sigma_delta_map[] =
+{
+  { LSTRKEY( "setup" ),       LFUNCVAL( sigma_delta_setup ) },
+  { LSTRKEY( "close" ),       LFUNCVAL( sigma_delta_close ) },
+  //{ LSTRKEY( "setpwmduty" ),  LFUNCVAL( sigma_delta_setpwmduty ) },
+  { LSTRKEY( "setprescale" ), LFUNCVAL( sigma_delta_setprescale ) },
+  { LSTRKEY( "setduty" ),     LFUNCVAL( sigma_delta_setduty ) },
+  { LNILKEY, LNILVAL }
+};
+
+NODEMCU_MODULE(SIGMADELTA, "sigma_delta", sigma_delta_map, NULL);

components/platform/include/platform.h

@@ -68,6 +68,18 @@ void platform_uart_send( unsigned id, uint8_t data );
 int platform_uart_set_flow_control( unsigned id, int type );
 
 
+// *****************************************************************************
+// Sigma-Delta subsection
+int platform_sigma_delta_exists( unsigned channel );
+
+uint8_t platform_sigma_delta_setup( uint8_t channel, uint8_t gpio_num );
+uint8_t platform_sigma_delta_close( uint8_t channel );
+// PWM emulation not possible, code kept for future reference
+//uint8_t platform_sigma_delta_set_pwmduty( uint8_t channel, uint8_t duty );
+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 );
+
+
 // Internal flash erase/write functions
 
 uint32_t platform_flash_get_sector_of_address( uint32_t addr );

components/platform/platform.c

@@ -1,5 +1,6 @@
 #include "platform.h"
 #include "driver/console.h"
+#include "driver/sigmadelta.h"
 #include <stdio.h>
 
 int platform_init (void)
@@ -58,3 +59,82 @@ void platform_uart_send( unsigned id, uint8_t data )
   if (id == CONSOLE_UART)
     putchar (data);
 }
+
+// *****************************************************************************
+// Sigma-Delta platform interface
+
+static gpio_num_t platform_sigma_delta_channel2gpio[SIGMADELTA_CHANNEL_MAX];
+
+int platform_sigma_delta_exists( unsigned channel ) {
+  return (channel < SIGMADELTA_CHANNEL_MAX);
+}
+
+uint8_t platform_sigma_delta_setup( uint8_t channel, uint8_t gpio_num )
+{
+#if 0
+  // signal generator can't be stopped this way
+  // stop signal generator
+  if (ESP_OK != sigmadelta_set_prescale( channel, 0 ))
+    return 0;
+#endif
+
+  // note channel to gpio assignment
+  platform_sigma_delta_channel2gpio[channel] = gpio_num;
+
+  return ESP_OK == sigmadelta_set_pin( channel, gpio_num ) ? 1 : 0;
+}
+
+uint8_t platform_sigma_delta_close( uint8_t channel )
+{
+#if 0
+  // Note: signal generator can't be stopped this way
+  // stop signal generator
+  if (ESP_OK != sigmadelta_set_prescale( channel, 0 ))
+    return 0;
+#endif
+
+  gpio_set_level( platform_sigma_delta_channel2gpio[channel], 1 );
+  gpio_config_t cfg;
+  // force pin back to GPIO
+  cfg.intr_type = GPIO_INTR_DISABLE;
+  cfg.mode = GPIO_MODE_OUTPUT;  // essential to switch IO matrix to GPIO
+  cfg.pull_down_en = GPIO_PULLDOWN_DISABLE;
+  cfg.pull_up_en = GPIO_PULLUP_ENABLE;
+  cfg.pin_bit_mask = 1 << platform_sigma_delta_channel2gpio[channel];
+  if (ESP_OK != gpio_config( &cfg ))
+    return 0;
+
+  // and set it finally to input with pull-up enabled
+  cfg.mode = GPIO_MODE_INPUT;
+
+  return ESP_OK == gpio_config( &cfg ) ? 1 : 0;
+}
+
+#if 0
+// PWM emulation not possible, code kept for future reference
+uint8_t platform_sigma_delta_set_pwmduty( uint8_t channel, uint8_t duty )
+{
+  uint8_t target = 0, prescale = 0;
+
+  target = duty > 128 ? 256 - duty : duty;
+  prescale = target == 0 ? 0 : target-1;
+
+  //freq = 80000 (khz) /256 /duty_target * (prescale+1)
+  if (ESP_OK != sigmadelta_set_prescale( channel, prescale ))
+    return 0;
+  if (ESP_OK != sigmadelta_set_duty( channel, duty-128 ))
+    return 0;
+
+  return 1;
+}
+#endif
+
+uint8_t platform_sigma_delta_set_prescale( uint8_t channel, uint8_t prescale )
+{
+  return ESP_OK == sigmadelta_set_prescale( channel, prescale ) ? 1 : 0;
+}
+
+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;
+}

docs/en/modules/sigma-delta.md

@@ -0,0 +1,72 @@
+# Sigma-delta Module
+| Since  | Origin / Contributor  | Maintainer  | Source  |
+| :----- | :-------------------- | :---------- | :------ |
+| 2017-01-13 | [Arnim Läuger](https://github.com/devsaurus) | [Arnim Läuger](https://github.com/devsaurus) | [sigma_delta.c](../../../app/modules/sigma_delta.c)|
+
+This module provides access to the [sigma-delta](https://en.wikipedia.org/wiki/Delta-sigma_modulation) component. It's a hardware signal generator that can be routed to any of the output GPIOs.
+
+The signal generation is controlled by the [`setprescale()`](#sigma_deltasetprescale) and [`setduty()`](#sigma_deltasetduty) functions.
+
+## sigma_delta.close()
+Reenables GPIO functionality at the related pin.
+
+#### Syntax
+`sigma_delta.close(channel)`
+
+#### Parameters
+- `channel` 0~7, sigma-delta channel index
+
+#### Returns
+`nil`
+
+## sigma_delta.setprescale()
+Sets the prescale value.
+
+#### Syntax
+`sigma_delta.setprescale(channel, value)
+
+#### Parameters
+- `channel` 0~7, sigma-delta channel index
+- `value` prescale 1 to 255
+
+#### Returns
+`nil`
+
+#### See also
+[`sigma_delta.setduty()`](#sigma_deltasetduty)
+
+## sigma_delta.setduty()
+Sets the duty value.
+
+#### Syntax
+`sigma_delta.setduty(channel, value)`
+
+#### Parameters
+- `channel` 0~7, sigma-delta channel index
+- `value` duty -128 to 127
+
+#### Returns
+`nil`
+
+#### See also
+[`sigma_delta.setprescale()`](#sigma_deltasetprescale)
+
+## sigma_delta.setup()
+Routes the sigma-delta channel to the specified pin. Target prescale and duty values should be applied prior to enabling the output with this command.
+
+#### Syntax
+`sigma_delta.setup(channel, pin)`
+
+#### Parameters
+- `channel` 0~7, sigma-delta channel index
+- `pin` 0~33, IO index
+
+#### Returns
+`nil`
+
+#### Example
+```lua
+sigma_delta.setprescale(0, 128)
+sigma_delta.setduty(0, 0)
+sigma_delta.setup(0, 4)
+```

mkdocs.yml

@@ -34,6 +34,7 @@ pages:
         - 'bthci':       'en/modules/bthci.md'
         - 'file':        'en/modules/file.md'
         - 'node':        'en/modules/node.md'
+        - 'sigma delta': 'en/modules/sigma-delta.md'
         - 'struct':      'en/modules/struct.md'
         - 'uart':        'en/modules/uart.md'
         - 'wifi':        'en/modules/wifi.md'