extmod/machine_spi: Factor out software SPI code from esp8266 to extmod.

2 files changed, 50 insertions, 0 deletions

diff --git a/extmod/machine_spi.c b/extmod/machine_spi.c
index 1c64cf511..3a34b7fb0 100644
--- a/extmod/machine_spi.c
+++ b/extmod/machine_spi.c
@@ -32,6 +32,43 @@
 
 #if MICROPY_PY_MACHINE_SPI
 
+void mp_machine_soft_spi_transfer(mp_obj_base_t *self_in, size_t len, const uint8_t *src, uint8_t *dest) {
+    mp_machine_soft_spi_obj_t *self = (mp_machine_soft_spi_obj_t*)self_in;
+    // only MSB transfer is implemented
+    uint32_t delay_half = 500000 / self->baudrate + 1;
+    for (size_t i = 0; i < len; ++i) {
+        uint8_t data_out = src[i];
+        uint8_t data_in = 0;
+        for (int j = 0; j < 8; ++j, data_out <<= 1) {
+            mp_hal_pin_write(self->mosi, (data_out >> 7) & 1);
+            if (self->phase == 0) {
+                mp_hal_delay_us_fast(delay_half);
+                mp_hal_pin_write(self->sck, 1 - self->polarity);
+            } else {
+                mp_hal_pin_write(self->sck, 1 - self->polarity);
+                mp_hal_delay_us_fast(delay_half);
+            }
+            data_in = (data_in << 1) | mp_hal_pin_read(self->miso);
+            if (self->phase == 0) {
+                mp_hal_delay_us_fast(delay_half);
+                mp_hal_pin_write(self->sck, self->polarity);
+            } else {
+                mp_hal_pin_write(self->sck, self->polarity);
+                mp_hal_delay_us_fast(delay_half);
+            }
+        }
+        if (dest != NULL) {
+            dest[i] = data_in;
+        }
+
+        // Some ports need a regular callback, but probably we don't need
+        // to do this every byte, or even at all.
+        #ifdef MICROPY_EVENT_POLL_HOOK
+        MICROPY_EVENT_POLL_HOOK;
+        #endif
+    }
+}
+
 STATIC void mp_machine_spi_transfer(mp_obj_t self, size_t len, const void *src, void *dest) {
     mp_obj_base_t *s = (mp_obj_base_t*)MP_OBJ_TO_PTR(self);
     mp_machine_spi_p_t *spi_p = (mp_machine_spi_p_t*)s->type->protocol;
diff --git a/extmod/machine_spi.h b/extmod/machine_spi.h
index 35a911d91..e1922c6e8 100644
--- a/extmod/machine_spi.h
+++ b/extmod/machine_spi.h
@@ -28,12 +28,25 @@
 #define MICROPY_INCLUDED_EXTMOD_MACHINE_SPI_H
 
 #include "py/obj.h"
+#include "py/mphal.h"
 
 // SPI protocol
 typedef struct _mp_machine_spi_p_t {
     void (*transfer)(mp_obj_base_t *obj, size_t len, const uint8_t *src, uint8_t *dest);
 } mp_machine_spi_p_t;
 
+typedef struct _mp_machine_soft_spi_obj_t {
+    mp_obj_base_t base;
+    uint32_t baudrate;
+    uint8_t polarity;
+    uint8_t phase;
+    mp_hal_pin_obj_t sck;
+    mp_hal_pin_obj_t mosi;
+    mp_hal_pin_obj_t miso;
+} mp_machine_soft_spi_obj_t;
+
+void mp_machine_soft_spi_transfer(mp_obj_base_t *self, size_t len, const uint8_t *src, uint8_t *dest);
+
 MP_DECLARE_CONST_FUN_OBJ(mp_machine_spi_read_obj);
 MP_DECLARE_CONST_FUN_OBJ(mp_machine_spi_readinto_obj);
 MP_DECLARE_CONST_FUN_OBJ(mp_machine_spi_write_obj);