Decouple the layer stacks by using function pointers that allow interactions between the stacks by pointing to a function rather than full import of the header. This will follow the higher levels of RF and UART stack interactions with applications themselves while allowing easier debugging.

This is a push to both clean, optimize, and potentially fix bugs such as corrupted telemetry data possibly getting sent to proxy.

Correct Method Example - Command Application

The command application "opens" a port from the RF receive stack which just places a function pointer to the command application PUT() function using a standardized FIFO interface. The pointer is stored in an array where the index is the "port".

To assign the command application through a function pointer the initialization in main{} is performed:

//Open RX RF service ports (Transport Layer)
rf_rx_service_open(2, app_command_rf_rx_put, 0); // RF Command Link, not safe for broadcast reception

When a data packet at the transport layer level is received the RF network stack uses the assigned port to call the correct standardized PUT() function in the Command application:

void rf_rx_stack_rx(unsigned char service_number, unsigned char *data, unsigned char payload_len){
    //Recieved a new uart packet from external device
    //ALL APPLICATIONS MUST BUFFER AS FULL UART HIGH LEVEL FRAME
    if((service_number <RF_SERVICE_ELEMENT_COUNT) && (srvc_open_func_ptrs[service_number] != 0)){
            (*srvc_open_func_ptrs[service_number]) (data, service_number);
        }
    else{
        __no_operation(); //Bad service port or registration, not a valid pointer in array.
    }
}

Command Application interacts with RF receive through this PUT() function the is used through a function pointer.

void app_command_rf_rx_put(unsigned char *packet){
//Put into the same local command queue
put_fifo_sram(&app_command_rx_fifo_state_machine, packet);
}

It is important to realize that:

Command application never imported the RF Network Stack header
RF Network Stack never imported Command application

Incorrect Implementation

Note below that the includes for "rf_transport.h" (layer 4) directly imported "rf.h" (layer 2) and this is unwanted and causing both headers to be coupled. This breaks the modular desirement and creates blurred interfaces between layers.

/* -- Includes -- */

/* standard includes */
#include "cc430f6137.h"
#include "rf_transport.h"

/* faraday rf layer 2 include */
#include "rf.h"

/* faraday rf layer 4 service include */
#include "rf_service.h"

/* faraday fifo include */
#include "../Ring_Buffers/FIFO.h"

/* faraday hardware allocation include */
#include "../REVA_Faraday.h"

/* faraday gpio hardware abstraction functions */
#include "../HAL/GPIO.h"

RF Layer 2 (rf.c)

Calls To Layer 4 (rf_transport.h)

Lines

337 - rf_transport_parse()
343 - rf_transport_parse()

These references are in rf_housekeeping() and simply checking the transport FIFO for new data from Layer 4 to Layer 2.

void rf_housekeeping(void){
    __no_operation();
    unsigned char status;
    if(rf_check_tx_fifo() && !transmitting_flag){
        ReceiveOff();
        rf_get_next_tx_fifo();
        }
    else if(rf_datalink_rx_fifo_state_machine.inwaiting>0){
        //Get packet from queue
        status = get_fifo(&rf_datalink_rx_fifo_state_machine, &rf_datalink_rx_fifo_buffer, rf_rx_datalink_buffer);

        //Parse received packet
        rf_datalink_parse(&rf_rx_datalink_buffer);

        //Determine destination of RX'd packet
        if(strstr((char *)rf_datalink_packet_rx_struct.destination_callsign, (char *)local_callsign) != NULL){
            if(rf_datalink_packet_rx_struct.destination_identifier == local_device_id){
                //__no_operation(); //This device!
                rf_transport_parse((unsigned char *)rf_datalink_packet_rx_struct.payload, 0);
            }
        }

        else if(*strstr((char *)rf_datalink_packet_rx_struct.destination_callsign, (char *)"CQCQCQ")){
            //__no_operation(); //Broadcast
                rf_transport_parse((unsigned char *)rf_datalink_packet_rx_struct.payload, 1);
        }

        else{
            //__no_operation(); //All others
        }
    }
    else{
    }
}

Layer 4 (rf_transport.c)

rf_transport.c includes both layer 2 and rf service headers:

/* faraday rf layer 2 include */
#include "rf.h"

/* faraday rf layer 4 service include */
#include "rf_service.h"

rf.h

Line

48 - rf_tx_datalink_packet()

rf_service.h

Line

91 - rf_rx_service_broadcast_rule_get()
93 - rf_rx_stack_rx()
98 - rf_rx_stack_rx()

Layer 4 Services (rf_services.h)

This layer doesn't seem to have any of its own import issues but it is also a weird header to have.

FaradayRF / Faraday-Firmware

Decouple RF Packet Functions - Avoid Imports #74