From 1d2dfa955d679b43e0fd976fb1c621171f609311 Mon Sep 17 00:00:00 2001
From: Daniel Thompson <daniel@redfelineninja.org.uk>
Date: Sat, 18 Jan 2020 20:53:15 +0000
Subject: [PATCH] boards: Add support for active high buttons

The button on the PineTime isn't a simple pull low design. Instead
the switch is connected across two GPIO pins *and* has external
pull downs on both pins. This circuit requires special handling since
it must be active high and we need to configure the other pin as an
output for the pin to work correctly.
---
 src/boards.c | 24 +++++++++++++-----------
 src/boards.h |  4 ++++
 2 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/src/boards.c b/src/boards.c
index ab83a71..0521b2b 100644
--- a/src/boards.c
+++ b/src/boards.c
@@ -42,20 +42,22 @@
 //------------- IMPLEMENTATION -------------//
 void button_init(uint32_t pin)
 {
-  if ( BUTTON_PULL == NRF_GPIO_PIN_PULLDOWN )
-  {
-    nrf_gpio_cfg_sense_input(pin, BUTTON_PULL, NRF_GPIO_PIN_SENSE_HIGH);
-  }
-  else
-  {
-    nrf_gpio_cfg_sense_input(pin, BUTTON_PULL, NRF_GPIO_PIN_SENSE_LOW);
-  }
+  nrf_gpio_cfg_sense_input(pin, BUTTON_PULL, NRF_GPIO_PIN_SENSE_LOW);
+#ifdef BUTTON_ENABLE
+  /*
+   * BUTTON_ENABLE is used when a switch is connected to another GPIO pin
+   * rather than the Vcc or ground. In the bootloader we'll just permanently
+   * push the enable pin to whatever value the sense pin thinks is the
+   * active one.
+   */
+  nrf_gpio_cfg_output(BUTTON_ENABLE);
+  nrf_gpio_pin_write(BUTTON_ENABLE, BUTTON_ACTIVE);
+#endif
 }
 
 bool button_pressed(uint32_t pin)
 {
-  uint32_t const active_state = (BUTTON_PULL == NRF_GPIO_PIN_PULLDOWN ? 1 : 0);
-  return nrf_gpio_pin_read(pin) == active_state;
+  return (nrf_gpio_pin_read(pin) == BUTTON_ACTIVE) ? true : false;
 }
 
 void board_init(void)
@@ -68,7 +70,7 @@ void board_init(void)
   NRF_CLOCK->TASKS_LFCLKSTART = 1UL;
 
   button_init(BUTTON_DFU);
-#ifndef BUTTON_FRESET
+#ifdef BUTTON_FRESET
   button_init(BUTTON_FRESET);
 #endif
   NRFX_DELAY_US(100); // wait for the pin state is stable
diff --git a/src/boards.h b/src/boards.h
index 1c6d8ed..28cc5c6 100644
--- a/src/boards.h
+++ b/src/boards.h
@@ -39,6 +39,10 @@
 #if !defined(BUTTON_FRESET) && BUTTONS_NUMBER > 1
 #define BUTTON_FRESET   BUTTON_2
 #endif
+#ifndef BUTTON_ACTIVE
+/* default to active-low signals */
+#define BUTTON_ACTIVE 0
+#endif
 
 // The primary LED is usually Red but not in all cases.
 #define LED_PRIMARY 0