Česká verze stránky o desce zdroje a patic pro "ISP" programování
Sockets and power supply board for AVR ISP programmer
Content: Introduction - Description - What would I do in other way - Download
View of the populated board:
Solder side view:
Electronics and particularly microcontrollers are only a hobby for me. I cannot afford any commercial
development tools. I usually make the tools myself. Luckily, the modern microcontrollers can be programmed
simply in a serial way. For example, the AVR microctrontrollers by Atmel, the serial programming is primarily
targeted for "In System Programming", i.e. to be programmed directly in the application. This usally determines
the construction of ISP programmers - they don't have a power supply and are powered from the programmed
target application. Problems arise, when a chip has to be programmed outside of an application, or is going
to be used in an application where ISP is not suitable or striaghtly impossible. This is why I designed the described
construction. I believe that it can be useful also for other ISP programmers, not just my biprog.
Detailed documentation can be found in the Download section. Have a look at the layout first. Some unusual
sockets are displayed there. In fact, there are not complete sockets, but as can be seen also on the photos,
these are sections of precision connectors.
There are several reasons for this solution:
- lower cost
- simplified board layout
- much less holes to drill (my sight is not as good anymore!)
- less force needed to insert and remove the programmed chip.
You might be surprised by the two identically connected IPS connectors "Kanda" on the board. There are two reasons
1) The board can be used to mutually connect and power two ISP programmers. In this way, one ISP programmer
can be upgraded or initially programmed from the other ISP programmer.
2) The board can be used for programming other chips than those which have "sockets" on the board. For this case,
a simple adapter from Kanda connector to the needed socket has to be used.
Crystal / External Clock switch
Most of the chips can be switched to external clock using fuses. If this happens, the chip couldn't be programmed anymore,
if there would be only a crystal on the board. That's why there is a clock signal source on the board, built from a CMOS
version of the 555 timer. The generated frequency is approximately 1MHz. CAUTION, the "classical" (bipolar) 555
cannot be used for such a high frequency!
Switch S1 is used to choose crystal or 555. If external signal is chosen, the blue LED2 is lit. The switch is of an unknown
type, salvaged from an old phone.
What to look after
Watch out for the wire interconnects beneath the ATtiny socket! It is necessary to insert two wires into a single hole
This board is not designed for biprog HW 2.1 and 3.0, so it is not possible to program AT89LP4052 and AT89LP2052
without a modification!
I discovered a drawback of the construction immediately after building it. The ATtiny26 has a different pinout than other
20-tin AVRs. Never mind, I said to myself, I will make a special adapter - I have two Kanda connectors there for this
purpose... But wait - I forgot the clock source!
How would I design the board today? I have two options:
So, if you consider building this construction, don't forget to add this connector!
- Add a MLW14G type connector. It would have 2 extra pins (compared to Kanda) for clock signal.
Adapters would be connected via this connector.
- Add a 2-pin keyed connector (e.g. PSH02-02). Adapters would be connected using one of the Kanda connectors
plus this two-pin connector. This solution is simpler to make but more complicated to use.
I would also be more generous with space and make the board bigger. Some of the chips are quite hard to remove from
To download, click the right mouse button and chose "Save target as ...".
Clicking the left mouse button opens the file in a new window.
Statistics since 16. 5. 2007
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Last updated 16. 5. 2007
Translated by wek at efton dot sk