jtag: improve detection of power switch being turned off

This can help printing data register when a mismatch
occurs.

jtag_xsvf_player.h

@@ -45,6 +45,7 @@ Arduino usage:
 
 #define XSVF_DEBUG 0
 #define XSVF_CALC_CSUM 1
+#define XSVF_IGNORE_NOMATCH 0
 
 #define		XCOMPLETE 0
 #define		XTDOMASK 1
@@ -372,7 +373,7 @@ static uint32_t xsvf_player_get_next_long(void) {
   return i;
 }
 
-static uint32_t xsvf_player_get_next_bytes(uint8_t* data, uint32_t count) {
+static void xsvf_player_get_next_bytes(uint8_t* data, uint32_t count) {
   while(count--) {
     *data++ = xsvf_player_next_byte();
   }
@@ -583,17 +584,19 @@ static uint8_t xsvf_jtag_is_tdo_as_expected(uint8_t use_mask)
 			expected &= mask;
 			actual &= mask;
 		}
+#if XSVF_IGNORE_NOMATCH != 1
 		if (expected != actual) {
 #if XSVF_DEBUG
     Serial.println(F("D...NO MATCH!"));
-#endif      
+#endif
 			return 0;
 		}
+#endif
 	}
 
 #if XSVF_DEBUG
     Serial.println(F("D...match!"));
-#endif    
+#endif
 	return 1;
 }
 
@@ -976,6 +979,12 @@ static void jtag_play_xsvf(jtag_port_t* port)
   if (xsvf->xcomplete) {
       Serial.println(F("Q-0,OK"));
   }
+  //the 3 pins must be low or else the vref might be triggered next time
+  digitalWrite(port->tms, 0);
+  digitalWrite(port->tdi, 0);
+  digitalWrite(port->tck, 0);
+  delay(100);
+
   // put the jtag port pins into High-Z (vref already is input)
   pinMode(port->tms, INPUT);
   pinMode(port->tdi, INPUT);