I moved back to IDE 1.6.9, and loaded a simple sketch (a few calcualtions, Serial I/O) - it loaded and ran without errors. Then I tried a slightly more complex sketch (LCD and RTC), and it blocked "Uploading" after the memory usage lines. I tried again with the second program and it loaded with the following output:
avrdude: Version 6.3, compiled on Jun 22 2016 at 16:05:21
Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
Copyright (c) 2007-2014 Joerg Wunsch
System wide configuration file is "C:\Users\Bob Gilman\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino2/etc/avrdude.conf"
Using Port : COM3
Using Programmer : arduino
Overriding Baud Rate : 115200
AVR Part : ATmega328P
Chip Erase delay : 9000 us
PAGEL : PD7
BS2 : PC2
RESET disposition : dedicated
RETRY pulse : SCK
serial program mode : yes
parallel program mode : yes
Timeout : 200
StabDelay : 100
CmdexeDelay : 25
SyncLoops : 32
ByteDelay : 0
PollIndex : 3
PollValue : 0x53
Memory Detail :
Block Poll Page Polled
Memory Type Mode Delay Size Indx Paged Size Size #Pages MinW MaxW ReadBack
eeprom 65 20 4 0 no 1024 4 0 3600 3600 0xff 0xff
flash 65 6 128 0 yes 32768 128 256 4500 4500 0xff 0xff
lfuse 0 0 0 0 no 1 0 0 4500 4500 0x00 0x00
hfuse 0 0 0 0 no 1 0 0 4500 4500 0x00 0x00
efuse 0 0 0 0 no 1 0 0 4500 4500 0x00 0x00
lock 0 0 0 0 no 1 0 0 4500 4500 0x00 0x00
calibration 0 0 0 0 no 1 0 0 0 0 0x00 0x00
signature 0 0 0 0 no 3 0 0 0 0 0x00 0x00
Programmer Type : Arduino
Description : Arduino
Hardware Version: 3
Firmware Version: 4.4
Vtarget : 0.3 V
Varef : 0.3 V
Oscillator : 28.800 kHz
SCK period : 3.3 us
avrdude: AVR device initialized and ready to accept instructions
Reading | ################################################## | 100% 0.00s
avrdude: Device signature = 0x1e950f (probably m328p)
avrdude: reading input file "C:\Users\BOBGIL~1\AppData\Local\Temp\build035381eb57ccce2bf9dc82d1a987f4d1.tmp/DS3231DSTmon.ino.hex"
avrdude: writing flash (19962 bytes):
Writing | ################################################## | 100% 3.27s
avrdude: 19962 bytes of flash written
avrdude: verifying flash memory against C:\Users\BOBGIL~1\AppData\Local\Temp\build035381eb57ccce2bf9dc82d1a987f4d1.tmp/DS3231DSTmon.ino.hex:
avrdude: load data flash data from input file C:\Users\BOBGIL~1\AppData\Local\Temp\build035381eb57ccce2bf9dc82d1a987f4d1.tmp/DS3231DSTmon.ino.hex:
avrdude: input file C:\Users\BOBGIL~1\AppData\Local\Temp\build035381eb57ccce2bf9dc82d1a987f4d1.tmp/DS3231DSTmon.ino.hex contains 19962 bytes
avrdude: reading on-chip flash data:
Reading | ################################################## | 100% 2.56s
avrdude: verifying ...
avrdude: 19962 bytes of flash verified
avrdude done. Thank you.
And now it won't load either sketch - using AVR 1.6.12, IDE 1.6.9 on Windows 10. IIRC, the problem started after I updated to AVR 1.6.12 - should I back up to an earlier release?
Thanks for any suggestions.
-Bob