RCP firmware

When using Silicon Labs hardware, developers have 2 options to build the RCP firmware

1. Either from the OpenThread repository

2. Directly within Simplicity Studio

   This first method will not be covered in this guide

Modify RCP firmware

In order to be woken-up on a specifc 802.15.4 packet some modificationare necessary in RCP firmware.

1. Modify ncp_base_radio.cpp located in gecko_sdk_x.x\util\third_party\openthread\src\ncp as following:

   extern "C"  void magic_packet_test(otRadioFrame *aFrame);
   
   void NcpBase::LinkRawReceiveDone(otRadioFrame *aFrame, otError aError)
   {
     uint8_t header = SPINEL_HEADER_FLAG;
   
     OT_ASSERT(aFrame->mIid < kSpinelHeaderMaxNumIID);
   
     header |= SPINEL_HEADER_IID(aFrame->mIid);
   
     magic_packet_test(aFrame);
   
     // Append frame header
     SuccessOrExit(mEncoder.BeginFrame(header, SPINEL_CMD_PROP_VALUE_IS, SPINEL_PROP_STREAM_RAW));
     SuccessOrExit(PackRadioFrame(aFrame, aError));
     SuccessOrExit(mEncoder.EndFrame());
   
     exit:
         return;
   }
   

   The LinkRawReceiveDone function is called on receipt of a IEEE 802.15.4 frame.

2. Create a magic_packet.c file in the RCP project directory and add the following content to it:

   #include <stdio.h>
   
   #include <openthread/ncp.h>
   #include "openthread-system.h"
   
   #include "em_gpio.h"
   #include "gpiointerrupt.h"
   
   #define ENTER_MAGIC_PKT_MODE_GPIO_PORT gpioPortD
   #define ENTER_MAGIC_PKT_MODE_GPIO_PIN  14
   
   #define MAGIC_PKT_FOUND_GPIO_PORT gpioPortD
   #define MAGIC_PKT_FOUND_GPIO_PIN  8
   
   uint8_t volatile magic_pkt_mode = 0;
   static otInstance* sInstance = NULL;
   
   /* Use falling edge of a GPIO to enter magic packet detection mode */
   void ENTER_MAGIC_PKT_MODE_GPIO_callback(void)
   {
     uint8_t v = GPIO_PinInGet(ENTER_MAGIC_PKT_MODE_GPIO_PORT, ENTER_MAGIC_PKT_MODE_GPIO_PIN);
   
     /* Check if falling edge */
     if (v == 0)
       magic_pkt_mode = 1;
   }
   
   /* Raise a GPIO when magic packet is detected */
   void magic_packet_test(otRadioFrame *aFrame)
   {
     uint16_t panId = *(uint16_t *)((aFrame->mPsdu) + 3);
     uint16_t dst = *(uint16_t *)((aFrame->mPsdu) + 5);
     uint16_t src = *(uint16_t *)((aFrame->mPsdu) + 7);
   
     /* Any other tests can be added there */
     if ((magic_pkt_mode == 1) && (panId == otLinkGetPanId(sInstance)) &&
         (dst == 0xFFFF) && (src == 0xFFFF))
     {
       GPIO_PinOutSet(MAGIC_PKT_FOUND_GPIO_PORT, MAGIC_PKT_FOUND_GPIO_PIN);
       magic_pkt_mode = 0;
     }
   }
   
   void magic_packet_init(otInstance *aInstance)
   {
     sInstance = aInstance;
         
     //GPIOINT_Init() and CMU_ClockEnable(cmuClock_GPIO) have already been called
   
     // Configure Button as input and enable interrupt
     GPIO_PinModeSet(ENTER_MAGIC_PKT_MODE_GPIO_PORT, ENTER_MAGIC_PKT_MODE_GPIO_PIN, gpioModeInputPull, 1);
     GPIO_ExtIntConfig(ENTER_MAGIC_PKT_MODE_GPIO_PORT,
                       ENTER_MAGIC_PKT_MODE_GPIO_PIN,
                       ENTER_MAGIC_PKT_MODE_GPIO_PIN,
                       false,
                       true,
                       true);
   
   
     // Register callback functions and enable interrupts
     GPIOINT_CallbackRegister(ENTER_MAGIC_PKT_MODE_GPIO_PIN, ENTER_MAGIC_PKT_MODE_GPIO_callback);
     GPIO_IntEnable(1<<ENTER_MAGIC_PKT_MODE_GPIO_PIN);
   
     // Configure LED as a push pull output for LED drive
     GPIO_PinModeSet(MAGIC_PKT_FOUND_GPIO_PORT, MAGIC_PKT_FOUND_GPIO_PIN, gpioModePushPull, 0);
   }
   

   We discriminate the magic packet here based on panId, SrcId and DstId of 802.15.4 received packet. We also use A GPIO to start searching for the magic packet. This code has been tested on BRD4166a only. You will have to modify MAGIC_PKT_FOUND_GPIO and ENTER_MAGIC_PKT_MODE_GPIO to have it work on another platform.

3. Call magic_packet_init() function from app_init():

   void app_init(void)
   {
     OT_SETUP_RESET_JUMP(argv);
   
     magic_packet_init(sInstance);
   }
   

Build and Flash the RCP

After compilation, flash the firmware into EFR32. Don't forget to add a bootloader. If you want to use printf for debugging, enable the Tiny printf component and the IOStream RTT component, and use a RTT console to display log.