main.cpp

/* SUIT pseudo bootloader
 * Created at the IETF 101 Hackathon
 * Receives a manifest to RAM and verifies it
 * https://os.mbed.com/compiler/#nav:/uart_pseudo_bootloader/main.cpp
 */
 
#include "mbed.h"
 
#define RXBUFFERSIZE  1024  // Size of RAM buffer for receiving the manifest
 
#define LED_RED    led1
#define LED_GREEN  led2
#define LED_BLUE   led3
 
uint8_t rxBuffer[RXBUFFERSIZE];
uint8_t *rxPtr = rxBuffer;
uint16_t manifestLen = 0;
 
/* Setup peripherals */ 
DigitalOut led1(LED1);
DigitalOut led2(LED2);
DigitalOut led3(LED3);
Serial pc(USBTX, USBRX); // tx, rx
 
int main() {
    // Turn on all LEDs
    LED_RED = 0;
    LED_GREEN = 0;
    LED_BLUE = 0;
    wait(0.5);
    // Turn off red and blue; just green is on
    LED_RED = 1;
    LED_BLUE = 1;
 
    pc.printf("***Welcome to SUIT pseudo bootloader!***\n");
    pc.printf("Length of your manifest in bytes?\n");
    pc.printf("(Send as hex word, e.g. if the length is 1024 bytes (0x400) send 0x04, 0x00.)\n");
 
    manifestLen = pc.getc() << 8;
    manifestLen += pc.getc();
    
    /* Catch buffer overflow */
    if(manifestLen > (uint16_t)RXBUFFERSIZE) {
        pc.printf("Maximum buffer size of %d bytes exceeded.\n", (uint16_t)RXBUFFERSIZE);
        LED_GREEN = 1;  // Turn green of
        while(1) {  // Trap for error state
            LED_RED = !LED_RED;
            wait(0.25);
        }
    }
    
    /* Receive from UART to RAM buffer */
    pc.printf("Waiting for %d bytes...\n", manifestLen);
    uint16_t i = 0;
    while(i < manifestLen) {
        rxBuffer[i] = pc.getc();
        i++;
        LED_BLUE = !LED_BLUE;  // Blink blue while receiving
        LED_BLUE = !LED_BLUE;
    }
    
    // TODO: Process rxBuffer (manifest) here
    
    LED_GREEN = 1;  // Turn off green LED
    for(i = 0; i < manifestLen; i++) {
        pc.putc(rxBuffer[i]);
        LED_BLUE = !LED_BLUE;  // Blink blue while tranceiving
        LED_BLUE = !LED_BLUE;
    }
 
    // Done, trap CPU
    while(1) {
        LED_GREEN = !LED_GREEN;  
        wait(0.5);
    }
}