From 4b2c99470ae27baf8dbbffd872117f9cf6bde566 Mon Sep 17 00:00:00 2001
From: Stefan Rueger <stefan.rueger@urclocks.com>
Date: Wed, 17 Apr 2024 19:11:32 +0100
Subject: [PATCH] Make default eeprom readback values 0xff for STK500 v1
 programmer

---
 src/stk500.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/stk500.c b/src/stk500.c
index 6f7f7156..d2446f39 100644
--- a/src/stk500.c
+++ b/src/stk500.c
@@ -489,6 +489,8 @@ static int stk500_initialize(const PROGRAMMER *pgm, const AVRPART *p) {
   if ((m = avr_locate_eeprom(p))) {
     buf[11] = m->readback[0];
     buf[12] = m->readback[1];
+    if(!buf[11] && !buf[12])    // Make default readback values 0xff for eeproms
+      buf[11] = buf[12] = 0xff;
     buf[15] = (m->size >> 8) & 0x00ff;
     buf[16] = m->size & 0x00ff;
   } else {