I've been trying to program an Attiny84 on a custom board that I designed via an USBasp programmer, but I keep getting a "verification error" from avrdude. It sounds like this is a pretty common problem, but I haven't found any clues as to what actions I should take next.
Below is the complete log, and just by looking at it, it's obvious the attiny84 is communicating (at least to some degree), so I highly doubt it's a hardware problem. However, since the attiny84 is powered from an Li-ion and the programmer is 5V, I have a voltage translator separating them. It shouldn't make any difference, but just in case. I'm using the attiny core v1.0.2 by David Mellis and Arduino 1.8.2.
Sketch uses 702 bytes (8%) of program storage space. Maximum is 8192 bytes.
Global variables use 9 bytes (1%) of dynamic memory, leaving 503 bytes for local variables. Maximum is 512 bytes.
C:\Users\Caleb\Arduino\hardware\tools\avr/bin/avrdude -CC:\Users\Caleb\Arduino\hardware\tools\avr/etc/avrdude.conf -v -pattiny84 -cusbasp -Pusb -Uflash:w:C:\Users\Caleb\AppData\Local\Temp\arduino_build_32384/Blink.ino.hex:i
avrdude: Version 6.3, compiled on Jan 17 2017 at 12:00:53
Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
Copyright (c) 2007-2014 Joerg Wunsch
System wide configuration file is "C:\Users\Caleb\Arduino\hardware\tools\avr/etc/avrdude.conf"
Using Port : usb
Using Programmer : usbasp
avrdude: Warning: cannot open USB device: Function not implemented
AVR Part : ATtiny84
Chip Erase delay : 4500 us
PAGEL : P00
BS2 : P00
RESET disposition : possible i/o
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 6 4 0 no 512 4 0 4000 4500 0xff 0xff
flash 65 6 32 0 yes 8192 64 128 4500 4500 0xff 0xff
signature 0 0 0 0 no 3 0 0 0 0 0x00 0x00
lock 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
lfuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
hfuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
efuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
calibration 0 0 0 0 no 1 0 0 0 0 0x00 0x00
Programmer Type : usbasp
Description : USBasp, http://www.fischl.de/usbasp/
avrdude: auto set sck period (because given equals null)
avrdude: warning: cannot set sck period. please check for usbasp firmware update.
avrdude: AVR device initialized and ready to accept instructions
Reading | ################################################## | 100% 0.00s
avrdude: Device signature = 0x1e930c (probably t84)
avrdude: NOTE: "flash" memory has been specified, an erase cycle will be performed
To disable this feature, specify the -D option.
avrdude: erasing chip
avrdude: auto set sck period (because given equals null)
avrdude: warning: cannot set sck period. please check for usbasp firmware update.
avrdude: reading input file "C:\Users\Caleb\AppData\Local\Temp\arduino_build_32384/Blink.ino.hex"
avrdude: writing flash (702 bytes):
Writing | ################################################## | 100% 0.37s
avrdude: 702 bytes of flash written
avrdude: verifying flash memory against C:\Users\Caleb\AppData\Local\Temp\arduino_build_32384/Blink.ino.hex:
avrdude: load data flash data from input file C:\Users\Caleb\AppData\Local\Temp\arduino_build_32384/Blink.ino.hex:
avrdude: input file C:\Users\Caleb\AppData\Local\Temp\arduino_build_32384/Blink.ino.hex contains 702 bytes
avrdude: reading on-chip flash data:
Reading | ################################################## | 100% 0.23s
avrdude: verifying ...
avrdude: verification error, first mismatch at byte 0x0000
0x00 != 0x27
avrdude: verification error; content mismatch
avrdude done. Thank you.
the selected serial port
does not exist or your board is not connected