nrf24l01: Improve test to add RP2 support, fix ESP32.

Use explicit pin numbers to instantiate the SPI interface on RP2.
On ESP32 use SoftSPI(...) rather than SPI(-1, ...).

Update terminology to initiator/responder.

Tested with two Pico boards.

micropython/drivers/radio/nrf24l01/nrf24l01test.py

@@ -3,23 +3,29 @@
 import usys
 import ustruct as struct
 import utime
-from machine import Pin, SPI
+from machine import Pin, SPI, SoftSPI
 from nrf24l01 import NRF24L01
 from micropython import const
 
-# Slave pause between receiving data and checking for further packets.
+# Responder pause between receiving data and checking for further packets.
 _RX_POLL_DELAY = const(15)
-# Slave pauses an additional _SLAVE_SEND_DELAY ms after receiving data and before
+# Responder pauses an additional _RESPONER_SEND_DELAY ms after receiving data and before
-# transmitting to allow the (remote) master time to get into receive mode. The
+# transmitting to allow the (remote) initiator time to get into receive mode. The
-# master may be a slow device. Value tested with Pyboard, ESP32 and ESP8266.
+# initiator may be a slow device. Value tested with Pyboard, ESP32 and ESP8266.
-_SLAVE_SEND_DELAY = const(10)
+_RESPONDER_SEND_DELAY = const(10)
 
 if usys.platform == "pyboard":
-    cfg = {"spi": 2, "miso": "Y7", "mosi": "Y8", "sck": "Y6", "csn": "Y5", "ce": "Y4"}
+    spi = SPI(2)  # miso : Y7, mosi : Y8, sck : Y6
+    cfg = {"spi": spi, "csn": "Y5", "ce": "Y4"}
 elif usys.platform == "esp8266":  # Hardware SPI
-    cfg = {"spi": 1, "miso": 12, "mosi": 13, "sck": 14, "csn": 4, "ce": 5}
+    spi = SPI(1)  # miso : 12, mosi : 13, sck : 14
+    cfg = {"spi": spi, "csn": 4, "ce": 5}
 elif usys.platform == "esp32":  # Software SPI
-    cfg = {"spi": -1, "miso": 32, "mosi": 33, "sck": 25, "csn": 26, "ce": 27}
+    spi = SoftSPI(sck=Pin(25), mosi=Pin(33), miso=Pin(32))
+    cfg = {"spi": spi, "csn": 26, "ce": 27}
+elif usys.platform == "rp2":  # Hardware SPI with explicit pin definitions
+    spi = SPI(0, sck=Pin(2), mosi=Pin(3), miso=Pin(4))
+    cfg = {"spi": spi, "csn": 5, "ce": 6}
 else:
     raise ValueError("Unsupported platform {}".format(usys.platform))
 
@@ -28,14 +34,11 @@ else:
 pipes = (b"\xe1\xf0\xf0\xf0\xf0", b"\xd2\xf0\xf0\xf0\xf0")
 
 
-def master():
+def initiator():
     csn = Pin(cfg["csn"], mode=Pin.OUT, value=1)
     ce = Pin(cfg["ce"], mode=Pin.OUT, value=0)
-    if cfg["spi"] == -1:
+    spi = cfg["spi"]
-        spi = SPI(-1, sck=Pin(cfg["sck"]), mosi=Pin(cfg["mosi"]), miso=Pin(cfg["miso"]))
     nrf = NRF24L01(spi, csn, ce, payload_size=8)
-    else:
-        nrf = NRF24L01(SPI(cfg["spi"]), csn, ce, payload_size=8)
 
     nrf.open_tx_pipe(pipes[0])
     nrf.open_rx_pipe(1, pipes[1])
@@ -46,7 +49,7 @@ def master():
     num_failures = 0
     led_state = 0
 
-    print("NRF24L01 master mode, sending %d packets..." % num_needed)
+    print("NRF24L01 initiator mode, sending %d packets..." % num_needed)
 
     while num_successes < num_needed and num_failures < num_needed:
         # stop listening and send packet
@@ -90,23 +93,20 @@ def master():
         # delay then loop
         utime.sleep_ms(250)
 
-    print("master finished sending; successes=%d, failures=%d" % (num_successes, num_failures))
+    print("initiator finished sending; successes=%d, failures=%d" % (num_successes, num_failures))
 
 
-def slave():
+def responder():
     csn = Pin(cfg["csn"], mode=Pin.OUT, value=1)
     ce = Pin(cfg["ce"], mode=Pin.OUT, value=0)
-    if cfg["spi"] == -1:
+    spi = cfg["spi"]
-        spi = SPI(-1, sck=Pin(cfg["sck"]), mosi=Pin(cfg["mosi"]), miso=Pin(cfg["miso"]))
     nrf = NRF24L01(spi, csn, ce, payload_size=8)
-    else:
-        nrf = NRF24L01(SPI(cfg["spi"]), csn, ce, payload_size=8)
 
     nrf.open_tx_pipe(pipes[1])
     nrf.open_rx_pipe(1, pipes[0])
     nrf.start_listening()
 
-    print("NRF24L01 slave mode, waiting for packets... (ctrl-C to stop)")
+    print("NRF24L01 responder mode, waiting for packets... (ctrl-C to stop)")
 
     while True:
         if nrf.any():
@@ -122,8 +122,8 @@ def slave():
                     led_state >>= 1
                 utime.sleep_ms(_RX_POLL_DELAY)
 
-            # Give master time to get into receive mode.
+            # Give initiator time to get into receive mode.
-            utime.sleep_ms(_SLAVE_SEND_DELAY)
+            utime.sleep_ms(_RESPONDER_SEND_DELAY)
             nrf.stop_listening()
             try:
                 nrf.send(struct.pack("i", millis))
@@ -144,7 +144,5 @@ print("NRF24L01 test module loaded")
 print("NRF24L01 pinout for test:")
 print("    CE on", cfg["ce"])
 print("    CSN on", cfg["csn"])
-print("    SCK on", cfg["sck"])
+print("    SPI on", cfg["spi"])
-print("    MISO on", cfg["miso"])
+print("run nrf24l01test.responder() on responder, then nrf24l01test.initiator() on initiator")
-print("    MOSI on", cfg["mosi"])
-print("run nrf24l01test.slave() on slave, then nrf24l01test.master() on master")