Add "pull" parameter to TouchIn ports

Author: todbot

locale/circuitpython.pot

@@ -1555,7 +1555,7 @@ msgstr ""
 msgid "No pulldown on pin; 1Mohm recommended"
 msgstr ""
 
-#: ports/raspberrypi/common-hal/touchio/TouchIn.c
+#: shared-module/touchio/TouchIn.c
 msgid "No pullup on pin; 1Mohm recommended"
 msgstr ""
 

ports/atmel-samd/common-hal/touchio/TouchIn.c

@@ -12,6 +12,7 @@
 #include "py/binary.h"
 #include "py/mphal.h"
 #include "shared-bindings/microcontroller/Pin.h"
+#include "shared-bindings/digitalio/Pull.h"
 #include "shared-bindings/touchio/TouchIn.h"
 
 // Native touchio only exists for SAMD21
@@ -38,7 +39,7 @@ static uint16_t get_raw_reading(touchio_touchin_obj_t *self) {
 }
 
 void common_hal_touchio_touchin_construct(touchio_touchin_obj_t *self,
-    const mcu_pin_obj_t *pin) {
+    const mcu_pin_obj_t *pin, const digitalio_pull_t pull) {
     if (!pin->has_touch) {
         raise_ValueError_invalid_pin();
     }

ports/espressif/common-hal/touchio/TouchIn.c

@@ -9,9 +9,10 @@
 #include "py/runtime.h"
 #include "peripherals/touch.h"
 #include "shared-bindings/microcontroller/Pin.h"
+#include "shared-bindings/digitalio/Pull.h"
 
 void common_hal_touchio_touchin_construct(touchio_touchin_obj_t *self,
-    const mcu_pin_obj_t *pin) {
+    const mcu_pin_obj_t *pin, const digitalio_pull_t pull) {
     if (pin->touch_channel == NO_TOUCH_CHANNEL) {
         raise_ValueError_invalid_pin();
     }

ports/raspberrypi/common-hal/touchio/TouchIn.c

@@ -64,12 +64,6 @@ CIRCUITPY_ALARM = 0
 # Default PICODVI on because it doesn't require much code in RAM to talk to HSTX.
 CIRCUITPY_PICODVI ?= 1
 
-# Our generic touchio uses a pull down and RP2350 A2 hardware doesn't work correctly.
-# So, turn generic touchio off because it doesn't work.
-# And use a "native" touchio that expects 1M pull-up resistor instead of pull-down
-CIRCUITPY_TOUCHIO = 1
-CIRCUITPY_TOUCHIO_USE_NATIVE ?= 1
-
 # delay in ms before calling cyw43_arch_init_with_country
 CIRCUITPY_CYW43_INIT_DELAY ?= 0
 

ports/raspberrypi/common-hal/touchio/TouchIn.h

@@ -31,22 +31,29 @@
 //|                print("touched!")"""
 //|
 
-//|     def __init__(self, pin: microcontroller.Pin) -> None:
+//|     def __init__(self, pin: microcontroller.Pin, pull: Optional[digitalio.Pull] = None) -> None:
 //|         """Use the TouchIn on the given pin.
 //|
 //|         :param ~microcontroller.Pin pin: the pin to read from"""
+//|         :param Optional[digitalio.Pull] pull: specify external pull resistor type. If None, assume pull-down or chip-specific implementation
 //|         ...
 //|
 static mp_obj_t touchio_touchin_make_new(const mp_obj_type_t *type,
-    size_t n_args, size_t n_kw, const mp_obj_t *args) {
-    // check number of arguments
-    mp_arg_check_num(n_args, n_kw, 1, 1, false);
+    size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
 
-    // 1st argument is the pin
-    const mcu_pin_obj_t *pin = validate_obj_is_free_pin(args[0], MP_QSTR_pin);
+    enum { ARG_pin, ARG_pull };
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_pin,  MP_ARG_OBJ | MP_ARG_REQUIRED },
+        { MP_QSTR_pull, MP_ARG_OBJ, {.u_obj = mp_const_none} },
+    };
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all_kw_array(n_args, n_kw, all_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    const mcu_pin_obj_t *pin = validate_obj_is_free_pin(args[ARG_pin].u_obj, MP_QSTR_pin);
+    const digitalio_pull_t pull = validate_pull(args[ARG_pull].u_obj, MP_QSTR_pull);
 
     touchio_touchin_obj_t *self = mp_obj_malloc(touchio_touchin_obj_t, &touchio_touchin_type);
-    common_hal_touchio_touchin_construct(self, pin);
+    common_hal_touchio_touchin_construct(self, pin, pull);
 
     return (mp_obj_t)self;
 }

ports/raspberrypi/common-hal/touchio/__init__.c

@@ -7,6 +7,7 @@
 #pragma once
 
 #include "common-hal/microcontroller/Pin.h"
+#include "shared-bindings/digitalio/Pull.h"
 
 #if CIRCUITPY_TOUCHIO_USE_NATIVE
 #include "common-hal/touchio/TouchIn.h"
@@ -16,7 +17,7 @@
 
 extern const mp_obj_type_t touchio_touchin_type;
 
-void common_hal_touchio_touchin_construct(touchio_touchin_obj_t *self, const mcu_pin_obj_t *pin);
+void common_hal_touchio_touchin_construct(touchio_touchin_obj_t *self, const mcu_pin_obj_t *pin, digitalio_pull_t pull);
 void common_hal_touchio_touchin_deinit(touchio_touchin_obj_t *self);
 bool common_hal_touchio_touchin_deinited(touchio_touchin_obj_t *self);
 bool common_hal_touchio_touchin_get_value(touchio_touchin_obj_t *self);

ports/raspberrypi/mpconfigport.mk

@@ -28,8 +28,9 @@
 //| For more information about working with the `touchio` module in CircuitPython,
 //| see `this Learn guide page <https://learn.adafruit.com/circuitpython-essentials/circuitpython-cap-touch>`_.
 //|
-//| **Limitations**: `touchio` is available on Raspberry Pi RP2040 builds,
-//| but not on RP2350, due to GPIO hardware limitations.
+//| **Limitations**: `touchio` on RP2350 must have a pull-up resistor to 3.3V
+//| instead of ground and set the `pull=Pull.UP` parameter when constructing
+//| a `TouchIn` object, due to GPIO hardware limitations.
 //|
 //| Example::
 //|

shared-bindings/touchio/TouchIn.c

@@ -12,34 +12,38 @@
 #include "py/mphal.h"
 #include "shared-bindings/touchio/TouchIn.h"
 #include "shared-bindings/microcontroller/Pin.h"
+#include "shared-bindings/digitalio/Pull.h"
 
-// This is a capacitive touch sensing routine using a single digital
-// pin.  The pin should be connected to the sensing pad, and to ground
+// This is a capacitive touch sensing routine using a single digital pin.
+// For pull==PULL_DOWN, the pin should be connected to the sensing pad and to ground
 // via a 1Mohm or thereabout drain resistor.  When a reading is taken,
 // the pin's capacitance is charged by setting it to a digital output
 // 'high' for a few microseconds, and then it is changed to a high
 // impedance input.  We measure how long it takes to discharge through
 // the resistor (around 50us), using a busy-waiting loop, and average
 // over N_SAMPLES cycles to reduce the effects of noise.
+// For the pull=PULL_UP case, the 1M resistor is connected to 3v3, the pin is
+// driven 'low' then measure how long it takes to go 'high'.
 
 #define N_SAMPLES 10
 #define TIMEOUT_TICKS 10000
 
 static uint16_t get_raw_reading(touchio_touchin_obj_t *self) {
 
     uint16_t ticks = 0;
-
+    // state to charge pin to: if pull-down or None, pull HIGH, if pull-up, pull LOW
+    bool pincharge = !(self->pull == PULL_UP);
     for (uint16_t i = 0; i < N_SAMPLES; i++) {
-        // set pad to digital output high for 10us to charge it
+        // set pad to digital output 'pincharge' for 10us to charge it
 
-        common_hal_digitalio_digitalinout_switch_to_output(self->digitalinout, true, DRIVE_MODE_PUSH_PULL);
+        common_hal_digitalio_digitalinout_switch_to_output(self->digitalinout, pincharge, DRIVE_MODE_PUSH_PULL);
         mp_hal_delay_us(10);
 
         // set pad back to an input and take some samples
 
         common_hal_digitalio_digitalinout_switch_to_input(self->digitalinout, PULL_NONE);
 
-        while (common_hal_digitalio_digitalinout_get_value(self->digitalinout)) {
+        while (common_hal_digitalio_digitalinout_get_value(self->digitalinout) == pincharge) {
             if (ticks >= TIMEOUT_TICKS) {
                 return TIMEOUT_TICKS;
             }
@@ -49,16 +53,22 @@ static uint16_t get_raw_reading(touchio_touchin_obj_t *self) {
     return ticks;
 }
 
-void common_hal_touchio_touchin_construct(touchio_touchin_obj_t *self, const mcu_pin_obj_t *pin) {
+void common_hal_touchio_touchin_construct(touchio_touchin_obj_t *self, const mcu_pin_obj_t *pin, const digitalio_pull_t pull) {
     common_hal_mcu_pin_claim(pin);
     self->digitalinout = mp_obj_malloc(digitalio_digitalinout_obj_t, &digitalio_digitalinout_type);
 
     common_hal_digitalio_digitalinout_construct(self->digitalinout, pin);
 
+    self->pull = pull;
+
     uint16_t raw_reading = get_raw_reading(self);
     if (raw_reading == TIMEOUT_TICKS) {
         common_hal_touchio_touchin_deinit(self);
-        mp_raise_ValueError(MP_ERROR_TEXT("No pulldown on pin; 1Mohm recommended"));
+        if (self->pull == PULL_UP) {
+            mp_raise_ValueError(MP_ERROR_TEXT("No pullup on pin; 1Mohm recommended"));
+        } else {
+            mp_raise_ValueError(MP_ERROR_TEXT("No pulldown on pin; 1Mohm recommended"));
+        }
     }
     self->threshold = raw_reading * 1.05 + 100;
 }

shared-bindings/touchio/TouchIn.h

@@ -15,6 +15,7 @@
 typedef struct {
     mp_obj_base_t base;
     digitalio_digitalinout_obj_t *digitalinout;
+    digitalio_pull_t pull;
     uint16_t threshold;
 } touchio_touchin_obj_t;