Enable CS "active-high" device support

Reference adafruit/Adafruit_CircuitPython_BusDevice#71

Add a new parameter cs_active_value for devices that require CS to use "active high" logic.

Author: michthom

shared-bindings/adafruit_bus_device/SPIDevice.c

@@ -48,6 +48,7 @@
 //|
 //|         :param ~busio.SPI spi: The SPI bus the device is on
 //|         :param ~digitalio.DigitalInOut chip_select: The chip select pin object that implements the DigitalInOut API.
+//|         :param bool cs_active_value: Set to true if your device requires CS to be active high. Defaults to false.
 //|         :param int extra_clocks: The minimum number of clock cycles to cycle the bus after CS is high. (Used for SD cards.)
 //|
 //|         Example::
@@ -73,10 +74,11 @@
 STATIC mp_obj_t adafruit_bus_device_spidevice_make_new(const mp_obj_type_t *type, size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
     adafruit_bus_device_spidevice_obj_t *self = m_new_obj(adafruit_bus_device_spidevice_obj_t);
     self->base.type = &adafruit_bus_device_spidevice_type;
-    enum { ARG_spi, ARG_chip_select, ARG_baudrate, ARG_polarity, ARG_phase, ARG_extra_clocks };
+    enum { ARG_spi, ARG_chip_select, ARG_cs_active_value, ARG_baudrate, ARG_polarity, ARG_phase, ARG_extra_clocks };
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_spi, MP_ARG_REQUIRED | MP_ARG_OBJ },
         { MP_QSTR_chip_select, MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
+        { MP_QSTR_cs_active_value, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
         { MP_QSTR_baudrate, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 100000} },
         { MP_QSTR_polarity, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
         { MP_QSTR_phase, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
@@ -87,7 +89,7 @@ STATIC mp_obj_t adafruit_bus_device_spidevice_make_new(const mp_obj_type_t *type
 
     busio_spi_obj_t *spi = args[ARG_spi].u_obj;
 
-    common_hal_adafruit_bus_device_spidevice_construct(MP_OBJ_TO_PTR(self), spi, args[ARG_chip_select].u_obj, args[ARG_baudrate].u_int, args[ARG_polarity].u_int,
+    common_hal_adafruit_bus_device_spidevice_construct(MP_OBJ_TO_PTR(self), spi, args[ARG_chip_select].u_obj, args[ARG_cs_active_value].u_bool, args[ARG_baudrate].u_int, args[ARG_polarity].u_int,
         args[ARG_phase].u_int, args[ARG_extra_clocks].u_int);
 
     if (args[ARG_chip_select].u_obj != MP_OBJ_NULL) {

shared-bindings/adafruit_bus_device/SPIDevice.h

@@ -43,7 +43,7 @@ extern const mp_obj_type_t adafruit_bus_device_spidevice_type;
 
 // Initializes the hardware peripheral.
 extern void common_hal_adafruit_bus_device_spidevice_construct(adafruit_bus_device_spidevice_obj_t *self, busio_spi_obj_t *spi,  digitalio_digitalinout_obj_t *cs,
-    uint32_t baudrate, uint8_t polarity, uint8_t phase, uint8_t extra_clocks);
+    bool cs_active_value, uint32_t baudrate, uint8_t polarity, uint8_t phase, uint8_t extra_clocks);
 extern mp_obj_t common_hal_adafruit_bus_device_spidevice_enter(adafruit_bus_device_spidevice_obj_t *self);
 extern void common_hal_adafruit_bus_device_spidevice_exit(adafruit_bus_device_spidevice_obj_t *self);
 

shared-module/adafruit_bus_device/SPIDevice.c

@@ -32,13 +32,14 @@
 #include "py/runtime.h"
 
 void common_hal_adafruit_bus_device_spidevice_construct(adafruit_bus_device_spidevice_obj_t *self, busio_spi_obj_t *spi,  digitalio_digitalinout_obj_t *cs,
-    uint32_t baudrate, uint8_t polarity, uint8_t phase, uint8_t extra_clocks) {
+    bool cs_active_value, uint32_t baudrate, uint8_t polarity, uint8_t phase, uint8_t extra_clocks) {
     self->spi = spi;
     self->baudrate = baudrate;
     self->polarity = polarity;
     self->phase = phase;
     self->extra_clocks = extra_clocks;
     self->chip_select = cs;
+    self->cs_active_value = cs_active_value;
 }
 
 mp_obj_t common_hal_adafruit_bus_device_spidevice_enter(adafruit_bus_device_spidevice_obj_t *self) {
@@ -66,14 +67,14 @@ mp_obj_t common_hal_adafruit_bus_device_spidevice_enter(adafruit_bus_device_spid
     }
 
     if (self->chip_select != MP_OBJ_NULL) {
-        common_hal_digitalio_digitalinout_set_value(MP_OBJ_TO_PTR(self->chip_select), false);
+        common_hal_digitalio_digitalinout_set_value(MP_OBJ_TO_PTR(self->chip_select), self->cs_active_value);
     }
     return self->spi;
 }
 
 void common_hal_adafruit_bus_device_spidevice_exit(adafruit_bus_device_spidevice_obj_t *self) {
     if (self->chip_select != MP_OBJ_NULL) {
-        common_hal_digitalio_digitalinout_set_value(MP_OBJ_TO_PTR(self->chip_select), true);
+        common_hal_digitalio_digitalinout_set_value(MP_OBJ_TO_PTR(self->chip_select), !(self->cs_active_value));
     }
 
     if (self->extra_clocks > 0) {

shared-module/adafruit_bus_device/SPIDevice.h

@@ -39,6 +39,7 @@ typedef struct {
     uint8_t phase;
     uint8_t extra_clocks;
     digitalio_digitalinout_obj_t *chip_select;
+    bool cs_active_value;
 } adafruit_bus_device_spidevice_obj_t;
 
 #endif // MICROPY_INCLUDED_ATMEL_SAMD_SHARED_MODULE_BUSDEVICE_SPIDEVICE_H