Merge pull request #9106 from wee-noise-makers/fourwire_optional_cs

shared-module/fourwire/FourWire.c: make the chip_select pin optional

Author: dhalbert

shared-bindings/fourwire/FourWire.c

@@ -47,7 +47,7 @@
 //|         spi_bus: busio.SPI,
 //|         *,
 //|         command: Optional[microcontroller.Pin],
-//|         chip_select: microcontroller.Pin,
+//|         chip_select: Optional[microcontroller.Pin],
 //|         reset: Optional[microcontroller.Pin] = None,
 //|         baudrate: int = 24000000,
 //|         polarity: int = 0,
@@ -79,7 +79,7 @@ STATIC mp_obj_t fourwire_fourwire_make_new(const mp_obj_type_t *type, size_t n_a
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_spi_bus, MP_ARG_REQUIRED | MP_ARG_OBJ },
         { MP_QSTR_command, MP_ARG_OBJ | MP_ARG_KW_ONLY, {.u_obj = mp_const_none} },
-        { MP_QSTR_chip_select, MP_ARG_OBJ | MP_ARG_KW_ONLY | MP_ARG_REQUIRED },
+        { MP_QSTR_chip_select, MP_ARG_OBJ | MP_ARG_KW_ONLY, {.u_obj = mp_const_none} },
         { MP_QSTR_reset, MP_ARG_OBJ | MP_ARG_KW_ONLY, {.u_obj = mp_const_none} },
         { MP_QSTR_baudrate, MP_ARG_INT | MP_ARG_KW_ONLY, {.u_int = 24000000} },
         { MP_QSTR_polarity, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
@@ -89,7 +89,7 @@ STATIC mp_obj_t fourwire_fourwire_make_new(const mp_obj_type_t *type, size_t n_a
     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 *command = validate_obj_is_free_pin_or_none(args[ARG_command].u_obj, MP_QSTR_command);
-    const mcu_pin_obj_t *chip_select = validate_obj_is_free_pin(args[ARG_chip_select].u_obj, MP_QSTR_chip_select);
+    const mcu_pin_obj_t *chip_select = validate_obj_is_free_pin_or_none(args[ARG_chip_select].u_obj, MP_QSTR_chip_select);
     const mcu_pin_obj_t *reset = validate_obj_is_free_pin_or_none(args[ARG_reset].u_obj, MP_QSTR_reset);
 
     mp_obj_t spi = mp_arg_validate_type(args[ARG_spi_bus].u_obj, &busio_spi_type, MP_QSTR_spi_bus);

shared-module/fourwire/FourWire.c

@@ -47,8 +47,6 @@ void common_hal_fourwire_fourwire_construct(fourwire_fourwire_obj_t *self,
     self->polarity = polarity;
     self->phase = phase;
 
-    common_hal_digitalio_digitalinout_construct(&self->chip_select, chip_select);
-    common_hal_digitalio_digitalinout_switch_to_output(&self->chip_select, true, DRIVE_MODE_PUSH_PULL);
 
     self->command.base.type = &mp_type_NoneType;
     if (command != NULL) {
@@ -66,7 +64,14 @@ void common_hal_fourwire_fourwire_construct(fourwire_fourwire_obj_t *self,
         common_hal_fourwire_fourwire_reset(self);
     }
 
-    common_hal_never_reset_pin(chip_select);
+    self->chip_select.base.type = &mp_type_NoneType;
+    if (chip_select != NULL) {
+        self->chip_select.base.type = &digitalio_digitalinout_type;
+        common_hal_digitalio_digitalinout_construct(&self->chip_select, chip_select);
+        common_hal_digitalio_digitalinout_switch_to_output(&self->chip_select, true, DRIVE_MODE_PUSH_PULL);
+        common_hal_never_reset_pin(chip_select);
+    }
+
 }
 
 void common_hal_fourwire_fourwire_deinit(fourwire_fourwire_obj_t *self) {
@@ -107,7 +112,9 @@ bool common_hal_fourwire_fourwire_begin_transaction(mp_obj_t obj) {
     }
     common_hal_busio_spi_configure(self->bus, self->frequency, self->polarity,
         self->phase, 8);
-    common_hal_digitalio_digitalinout_set_value(&self->chip_select, false);
+    if (self->chip_select.base.type != &mp_type_NoneType) {
+        common_hal_digitalio_digitalinout_set_value(&self->chip_select, false);
+    }
     return true;
 }
 
@@ -146,10 +153,12 @@ void common_hal_fourwire_fourwire_send(mp_obj_t obj, display_byte_type_t data_ty
         if (bits > 0) {
             buffer = buffer << (8 - bits);
             common_hal_busio_spi_write(self->bus, &buffer, 1);
-            // toggle CS to discard superfluous bits
-            common_hal_digitalio_digitalinout_set_value(&self->chip_select, true);
-            common_hal_mcu_delay_us(1);
-            common_hal_digitalio_digitalinout_set_value(&self->chip_select, false);
+            if (self->chip_select.base.type != &mp_type_NoneType) {
+                // toggle CS to discard superfluous bits
+                common_hal_digitalio_digitalinout_set_value(&self->chip_select, true);
+                common_hal_mcu_delay_us(1);
+                common_hal_digitalio_digitalinout_set_value(&self->chip_select, false);
+            }
         }
     } else {
         common_hal_digitalio_digitalinout_set_value(&self->command, data_type == DISPLAY_DATA);
@@ -158,9 +167,11 @@ void common_hal_fourwire_fourwire_send(mp_obj_t obj, display_byte_type_t data_ty
             // IC latches commands based on it.
             for (size_t i = 0; i < data_length; i++) {
                 common_hal_busio_spi_write(self->bus, &data[i], 1);
-                common_hal_digitalio_digitalinout_set_value(&self->chip_select, true);
-                common_hal_mcu_delay_us(1);
-                common_hal_digitalio_digitalinout_set_value(&self->chip_select, false);
+                if (self->chip_select.base.type != &mp_type_NoneType) {
+                    common_hal_digitalio_digitalinout_set_value(&self->chip_select, true);
+                    common_hal_mcu_delay_us(1);
+                    common_hal_digitalio_digitalinout_set_value(&self->chip_select, false);
+                }
             }
         } else {
             common_hal_busio_spi_write(self->bus, data, data_length);
@@ -170,7 +181,9 @@ void common_hal_fourwire_fourwire_send(mp_obj_t obj, display_byte_type_t data_ty
 
 void common_hal_fourwire_fourwire_end_transaction(mp_obj_t obj) {
     fourwire_fourwire_obj_t *self = MP_OBJ_TO_PTR(obj);
-    common_hal_digitalio_digitalinout_set_value(&self->chip_select, true);
+    if (self->chip_select.base.type != &mp_type_NoneType) {
+        common_hal_digitalio_digitalinout_set_value(&self->chip_select, true);
+    }
     common_hal_busio_spi_unlock(self->bus);
 }