Merge pull request micropython#564 from deanm1278/master

DM: added write_readinto to bitbangio

Author: tannewt

shared-bindings/bitbangio/SPI.c

@@ -236,6 +236,38 @@ STATIC mp_obj_t bitbangio_spi_readinto(size_t n_args, const mp_obj_t *args) {
 }
 MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(bitbangio_spi_readinto_obj, 2, 2, bitbangio_spi_readinto);
 
+//|   .. method:: SPI.write_readinto(buffer_out, buffer_in)
+//|
+//|     Write out the data in ``buffer_out`` while simultaneously reading data into ``buffer_in``.
+STATIC mp_obj_t bitbangio_spi_write_readinto(size_t n_args, const mp_obj_t *args) {
+    bitbangio_spi_obj_t *self = MP_OBJ_TO_PTR(args[0]);
+    raise_error_if_deinited(shared_module_bitbangio_spi_deinited(self));
+
+    mp_buffer_info_t bufinfoin;
+    mp_get_buffer_raise(args[2], &bufinfoin, MP_BUFFER_WRITE);
+
+    if (bufinfoin.len == 0) {
+        return mp_const_none;
+    }
+
+    mp_buffer_info_t bufinfoout;
+    mp_get_buffer_raise(args[1], &bufinfoout, MP_BUFFER_READ);
+
+    if (bufinfoout.len != bufinfoin.len) {
+        mp_raise_ValueError("buffers must be of equal length");
+    }
+
+    bool ok = shared_module_bitbangio_spi_transfer(self,
+                                            ((uint8_t*)bufinfoout.buf),
+                                            ((uint8_t*)bufinfoin.buf),
+                                            bufinfoin.len);
+    if (!ok) {
+        mp_raise_OSError(MP_EIO);
+    }
+    return mp_const_none;
+}
+MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(bitbangio_spi_write_readinto_obj, 3, 3, bitbangio_spi_write_readinto);
+
 STATIC const mp_rom_map_elem_t bitbangio_spi_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_deinit), MP_ROM_PTR(&bitbangio_spi_deinit_obj) },
     { MP_ROM_QSTR(MP_QSTR___enter__), MP_ROM_PTR(&default___enter___obj) },
@@ -247,6 +279,7 @@ STATIC const mp_rom_map_elem_t bitbangio_spi_locals_dict_table[] = {
 
     { MP_ROM_QSTR(MP_QSTR_readinto), MP_ROM_PTR(&bitbangio_spi_readinto_obj) },
     { MP_ROM_QSTR(MP_QSTR_write), MP_ROM_PTR(&bitbangio_spi_write_obj) },
+    { MP_ROM_QSTR(MP_QSTR_write_readinto), MP_ROM_PTR(&bitbangio_spi_write_readinto_obj) },
 };
 STATIC MP_DEFINE_CONST_DICT(bitbangio_spi_locals_dict, bitbangio_spi_locals_dict_table);
 

shared-bindings/bitbangio/SPI.h

@@ -56,4 +56,7 @@ extern bool shared_module_bitbangio_spi_write(bitbangio_spi_obj_t *self, const u
 // Reads in len bytes while outputting zeroes.
 extern bool shared_module_bitbangio_spi_read(bitbangio_spi_obj_t *self, uint8_t *data, size_t len);
 
+// Transfer out len bytes while reading len bytes
+extern bool shared_module_bitbangio_spi_transfer(bitbangio_spi_obj_t *self, const uint8_t *dout, uint8_t *din, size_t len);
+
 #endif // MICROPY_INCLUDED_SHARED_BINDINGS_BITBANGIO_SPI_H

shared-module/bitbangio/SPI.c

@@ -238,3 +238,69 @@ bool shared_module_bitbangio_spi_read(bitbangio_spi_obj_t *self, uint8_t *data,
     }
     return true;
 }
+
+// transfer
+bool shared_module_bitbangio_spi_transfer(bitbangio_spi_obj_t *self, const uint8_t *dout, uint8_t *din, size_t len) {
+    if (len > 0 && (!self->has_mosi || !self->has_miso) ) {
+        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError,
+            "Cannot transfer without MOSI and MISO pins."));
+    }
+    uint32_t delay_half = self->delay_half;
+
+    // only MSB transfer is implemented
+
+    // If a port defines MICROPY_PY_MACHINE_SPI_MIN_DELAY, and the configured
+    // delay_half is equal to this value, then the software SPI implementation
+    // will run as fast as possible, limited only by CPU speed and GPIO time.
+    #ifdef MICROPY_PY_MACHINE_SPI_MIN_DELAY
+    if (delay_half <= MICROPY_PY_MACHINE_SPI_MIN_DELAY) {
+        for (size_t i = 0; i < len; ++i) {
+            uint8_t data_out = dout[i];
+            uint8_t data_in = 0;
+            for (int j = 0; j < 8; ++j, data_out <<= 1) {
+                common_hal_digitalio_digitalinout_set_value(&self->mosi, (data_out >> 7) & 1);
+                common_hal_digitalio_digitalinout_set_value(&self->clock, 1 - self->polarity);
+                data_in = (data_in << 1) | common_hal_digitalio_digitalinout_get_value(&self->miso);
+                common_hal_digitalio_digitalinout_set_value(&self->clock, self->polarity);
+            }
+            din[i] = data_in;
+
+            if (dest != NULL) {
+                dest[i] = data_in;
+            }
+        }
+        return true;
+    }
+    #endif
+
+    for (size_t i = 0; i < len; ++i) {
+        uint8_t data_out = dout[i];
+        uint8_t data_in = 0;
+        for (int j = 0; j < 8; ++j, data_out <<= 1) {
+            common_hal_digitalio_digitalinout_set_value(&self->mosi, (data_out >> 7) & 1);
+            if (self->phase == 0) {
+                common_hal_mcu_delay_us(delay_half);
+                common_hal_digitalio_digitalinout_set_value(&self->clock, 1 - self->polarity);
+            } else {
+                common_hal_digitalio_digitalinout_set_value(&self->clock, 1 - self->polarity);
+                common_hal_mcu_delay_us(delay_half);
+            }
+            data_in = (data_in << 1) | common_hal_digitalio_digitalinout_get_value(&self->miso);
+            if (self->phase == 0) {
+                common_hal_mcu_delay_us(delay_half);
+                common_hal_digitalio_digitalinout_set_value(&self->clock, self->polarity);
+            } else {
+                common_hal_digitalio_digitalinout_set_value(&self->clock, self->polarity);
+                common_hal_mcu_delay_us(delay_half);
+            }
+        }
+        din[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
+    }
+    return true;
+}