RF24: Minor power optimization (#1069)

Author: tekka007

drivers/RF24/RF24.cpp

@@ -302,13 +302,14 @@ LOCAL bool RF24_sendMessage(const uint8_t recipient, const void *buf, const uint
 	                          RF24_CMD_WRITE_TX_PAYLOAD, (uint8_t *)buf, len, false );
 	// go, TX starts after ~10us, CE high also enables PA+LNA on supported HW
 	RF24_ce(HIGH);
+	delayMicroseconds(10); // datasheet: Pulse CE at least 10us
+	RF24_ce(LOW);
 	// timeout counter to detect HW issues
 	uint16_t timeout = 0xFFFF;
 	do {
 		RF24_status = RF24_getStatus();
 	} while  (!(RF24_status & ( _BV(RF24_MAX_RT) | _BV(RF24_TX_DS) )) && timeout--);
 	// timeout value after successful TX on 16Mhz AVR ~ 65500, i.e. msg is transmitted after ~36 loop cycles
-	RF24_ce(LOW);
 	// reset interrupts
 	RF24_setStatus(_BV(RF24_TX_DS) | _BV(RF24_MAX_RT) );
 	// Max retries exceeded