esp8266/machine_hspi: After an SPI write wait for last byte to transfer.

dpgeorge · dpgeorge · commit badaf3ecfe5d · 2017-12-14T10:43:18.000+11:00
Because otherwise the function can return with data still waiting to be clocked out, and CS might then be disabled before the SPI transaction is complete. Fixes issue adafruit#3487.
diff --git a/ports/esp8266/machine_hspi.c b/ports/esp8266/machine_hspi.c
@@ -65,6 +65,9 @@ STATIC void machine_hspi_transfer(mp_obj_base_t *self_in, size_t len, const uint
             spi_tx8fast(HSPI, src[i]);
             ++i;
         }
+        // wait for SPI transaction to complete
+        while (spi_busy(HSPI)) {
+        }
     } else {
         // we need to read and write data
 

Original file line number	Diff line number	Diff line change
`@@ -65,6 +65,9 @@ STATIC void machine_hspi_transfer(mp_obj_base_t *self_in, size_t len, const uint`
`65`	`65`	`spi_tx8fast(HSPI, src[i]);`
`66`	`66`	`++i;`
`67`	`67`	`}`
	`68`	`+ // wait for SPI transaction to complete`
	`69`	`+ while (spi_busy(HSPI)) {`
	`70`	`+ }`
`68`	`71`	`} else {`
`69`	`72`	`// we need to read and write data`
`70`	`73`