From dd4264ead7cdf63af84e68eaeb9470bee6f6b147 Mon Sep 17 00:00:00 2001
From: cpldcpu <cpldcpu@gmail.com>
Date: Sun, 22 Jun 2014 23:06:20 +0200
Subject: firmware: Changed handling of OSCCAL calibration

If the calibrated OSCAL was saved during programming it will be reloaded
before starting the bootloader, regardless whether it was entered or
not. This allows calibrating devices without PLL to 12 MHz.
---
 firmware/main.c | 40 +++++++++++++++++++++-------------------
 1 file changed, 21 insertions(+), 19 deletions(-)

diff --git a/firmware/main.c b/firmware/main.c
index 6a091a3..625f026 100644
--- a/firmware/main.c
+++ b/firmware/main.c
@@ -146,7 +146,7 @@ static void writeWordToPageBuffer(uint16_t data) {
   }    
 #endif
 
-#if (!OSCCAL_RESTORE) && OSCCAL_16_5MHz   
+#if OSCCAL_SAVE_CALIB
    if (currentAddress.w == BOOTLOADER_ADDRESS - TINYVECTOR_OSCCAL_OFFSET) {
       data = OSCCAL;
    }     
@@ -196,11 +196,21 @@ static void initHardware (void)
   WDTCR = 1<<WDP2 | 1<<WDP1 | 1<<WDP0; 
 #endif  
 
-  /* initialize  */
-  #if OSCCAL_RESTORE
-    osccal_default = OSCCAL;
-  #endif
-    
+
+  /* save default OSCCAL calibration  */
+#if OSCCAL_RESTORE_DEFAULT
+  osccal_default = OSCCAL;
+#endif
+  
+#if OSCCAL_SAVE_CALIB
+  // adjust clock to previous calibration value, so bootloader starts with proper clock calibration
+  unsigned char stored_osc_calibration = pgm_read_byte(BOOTLOADER_ADDRESS - TINYVECTOR_OSCCAL_OFFSET);
+  if (stored_osc_calibration != 0xFF) {
+    OSCCAL=stored_osc_calibration;
+    nop();
+  }
+#endif
+  
   usbDeviceDisconnect();  /* do this while interrupts are disabled */
   _delay_ms(300);  
   usbDeviceConnect();
@@ -220,19 +230,11 @@ static inline void leaveBootloader(void) {
   USB_INTR_ENABLE = 0;
   USB_INTR_CFG = 0;       /* also reset config bits */
 
-  #if OSCCAL_RESTORE
-    OSCCAL=osccal_default;
-    nop(); // NOP to avoid CPU hickup during oscillator stabilization
-  #elif OSCCAL_16_5MHz   
-    // adjust clock to previous calibration value, so user program always starts with same calibration
-    // as when it was uploaded originally
-    unsigned char stored_osc_calibration = pgm_read_byte(BOOTLOADER_ADDRESS - TINYVECTOR_OSCCAL_OFFSET);
-    if (stored_osc_calibration != 0xFF) {
-      OSCCAL=stored_osc_calibration;
-      nop();
-    }
-  #endif
-  
+#if OSCCAL_RESTORE_DEFAULT
+  OSCCAL=osccal_default;
+  nop(); // NOP to avoid CPU hickup during oscillator stabilization
+#endif
+    
  asm volatile ("rjmp __vectors - 4"); // jump to application reset vector at end of flash
   
  for (;;); // Make sure function does not return to help compiler optimize
-- 
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