About The Programmer
USBasp is a USB in-circuit programmer for Atmel AVR controllers. It simply consists of an ATMega48 and ATMega88 an ATMega8 and a couple of passive components. The programmer uses a firmware-only USB driver, no special USB controller is needed.
Features
- Works under multiple platforms. Linux, Mac OS X and Windows are tested.
- No special controllers or smd components are needed.
- Programming speed is up to 5kBytes/sec.
- SCK option to support targets with low clock speed (< 1,5MHz)
PARTLIST:
Partnumber
|
Value
|
Reichelt No
|
C1
|
4,7u
|
RAD 4,7/35
|
C2
|
100n
|
X7R-5 100N
|
C3, C4
|
22p
|
KERKO 22P
|
D1, D2
|
3V6 zener
|
ZF 3,6
|
CON1
|
USB-B
|
USB BW
|
CON2
|
10pol
|
WSL 10W
|
IC1
|
ATmega8-16
|
ATMEGA 8-16 (not
programmed!)
|
JP1, JP2
|
2pol 2,54mm
|
SL 1X36G 2,54
|
LED1
|
3mm LED green
|
LED 3MM 2MA GN
|
LED2
|
3mm LED red
|
LED 3MM 2MA RT
|
Q1
|
12Mhz
|
12,0000-HC49U-S
|
R1, R2
|
68
|
1/4W 68
|
R3
|
2,2k
|
1/4W 2,2k
|
R4, R5, R6, R7
|
270
|
1/4W 270
|
R8
|
10k
|
1/4W 10k
|
R9, R10
|
1k
|
1/4W 1k
|
M1, M2
|
Jumper
|
JUMPER 2,54GL SW
|
M3
|
Socket 28S
|
GS 28-S
|
M4
|
Case
|
TEKO 10007
|
M5
|
PCB
|
-
|
CIRCUIT DIAGRAM
Original circuit you will find in authors site: http://www.fischl.de/usbasp/
Download Firmware and circuit
Drivers
On Linux and MacOS X no kernel driver is needed.
Windows
requires a driver for USBasp. Please use this driver installation tool for
Windows:
Zadig - USB driver installation made easy
Zadig - USB driver installation made easy
NOTE: Impotance of zener http://vusb.wikidot.com/hardware
“Solution B: Level conversion on D+ and D- Level conversion with Zener diodes.
Instead of reducing the AVR’s power supply, we can limit the output voltage on D+ and D- with Zener diodes. We recommend 3.6 V low power types, those that look like 1N4148 (usually 500 mW or less). Low power types are required because they have less capacitance and thus cause less distortion on the data lines. And 3.6 V is better than 3.3 V because 3.3 V diodes yield only ca. 2.7 V in conjunction with an 1.5 kΩ (or more exactly 10 kΩ) pull-up resistor. With 3.3 V diodes, the device may not be detected reliably.
If you use Zener diodes for level conversion, please measure the voltage levels to make sure that the diodes you have chosen match the requirements.
Advantages of the Zener diode approach:
Low cost.
Easy to obtain.
Entire design can be at 5 V.
AVR can be clocked at high rates.
Disadvantages:
Not a clean solution, a compromise between all parameters must be found.
Zener diodes come with a broad range of characteristics, especially at low currents, results may not be reproducible.
High currents when sending high-level.
High level is different for signaling and in idle state because signaling uses high currents to drive the diodes while idle state is driven by a 1.5 kΩ pull-up resistor.”
