STK500V2 hangs with active Serial 0 on boot. Patch Provided.

[hayden-t]

If you have an active serial device (eg gps) hooked up to Serial 0 during boot, it hangs the boot loader as it thinks it is getting a new sketch but it never comes. Other boot loaders have the fix already, but not this one, making Serial 0 unusable for a permanently connected serial device.

This is a simple fix that checks if the incoming serial stream is a new sketch or not, and if it is not, then it continues the boot process and loads the existing sketch.

regards,
Hayden.

--- stk500boot.c    Sun Mar 30 12:51:46 2014
+++ stk500boot.c    Wed May 28 14:11:19 2014
@@ -272,6 +272,7 @@
    #define BOOTSIZE 2048
 #endif

+#define MAX_ERR_COUNT       10
 #define APP_END  (FLASHEND -(2*BOOTSIZE) + 1)

 /*
@@ -541,6 +542,7 @@
    unsigned char   msgBuffer[285];
    unsigned char   c, *p;
    unsigned char   isLeave = 0;
+    unsigned char   errCnt = 0;

    unsigned long   boot_timeout;
    unsigned long   boot_timer;
@@ -712,6 +714,18 @@
                        {
                            msgParseState   =   ST_GET_SEQ_NUM;
                            checksum        =   MESSAGE_START^0;
+                        }
+                        else
+                        {
+                            errCnt++;
+                            if(errCnt > MAX_ERR_COUNT)
+                            {
+                                msgParseState   =   99; //* we dont want it do anything
+                                isLeave         =   1;
+                                errCnt = 0;
+                                boot_state = 2;         // boot_state=2 bootloader timeout, jump to main 0x00000
+                                goto ENTER_APP_CODE;
+                            }
                        }
                        break;

@@ -1149,7 +1163,7 @@
    delay_ms(100);
 #endif

-
+ENTER_APP_CODE:
 #ifndef REMOVE_BOOTLOADER_LED
    PROGLED_DDR     &=  ~(1<<PROGLED_PIN);  // set to default
    PROGLED_PORT    &=  ~(1<<PROGLED_PIN);  // active low LED OFF