• See also Kit 128
• See also Kit 149
• See also Kit 150
• See also Kit 182

 
• Design For DIY Programmer Hardware Tester

 
• A working ICSP arrangement for DIY PIC Programmers.

 
• Latest News on DIY Programmers
  
  
• Upgrading your Firmware

Design For DIY Programmer Hardware Tester

A working ICSP arrangement for DIY USB PIC Programmers.

Notice that the schotty diode allows the DIY Programmer to feed its VCC without its VCC being shorted to the PIC's
normal power supply. A tiny DIP switch will also work in place of the diode. NOTE: the diode is very convenient when
developing the code, but it drops about 100mV of the VCC provided (but was never an issue in my designs. Simply do
NOT power the PIC while programming it.

The 27K is recommended to prevent VPP current from raising VCC. It can even be larger than this. You can use as low as 10K if a diode is placed in series at the MCLR pin, so that when VPP is applied nothing can conduct. But its a needless waste to have that second diode.

The reason for this schematic is to clarify how ICSP is driven by a DIY programmer.

The PIC programmer itself is designed to provide only enough VPP and VDD to program the device, nothing else. With the schottky diode, the VDD load of the product itself is ignored by the programmer while programming. The cap across the chip is very important, and can be as low as 0.01uF and as high as 0.1uF - but it can't be higher, otherwise the rise time needed to enter programming mode cannot be achieved. 

The other reason is the way PICs must enter programming mode. Some need to have VCC applied first, while others need to have VPP applied first. That two-step process, together with PGD and PGC at gnd, causes the PIC to enter
programming mode.

Bob Axtell

PGC, PGD, and GND pins of the PIC have to be connected to the programmer. The PGC and PGD pins need to be isolated from whatever is happening on the PCB when there PIC is. The GND can be connected, no problem.

The VDD pin of the PIC has to be connected to the programmer, and NOT connected to the VCC of the PCB, because the programmer does NOT have the power to power your PCB as well as the PIC. The normal way to isolate the VDD of the PIC and the VCC of the PCB is either with a schottky diode (or a jumper or switch). Never allow the PCB VCC to connect to the programmer, it won't work (and MIGHT be damaged).

Finally, the MCLR\ pin must be connected to the programmer, and not connected to the PCB- except that a small resistor (27K-33K is OK) can connect between the CHIP VDD and the CHIP MCLR\. This is used as an extra pullup. Microchip likes to isolate the MCLR signal with a diode because it believes that most programmers cannot handle this small amount applied to the VDD line when the MCLR is held at 13V. In fact, all DIY programmers are designed to handle that small bias without any problem. Its a lot of cost for very little return- so we don't recommend it when using OUR programmers.

That's all there is. 

This PDF schematic shows diagrams for testing all of DIY's PIC Programmers. User instructions are enclosed.

Not stated is the obvious: if NONE of the leds wink, there is a communication problem to the programmer, USB drivers, cable etc, although the internal PIC chip could also be inserted backwards or be otherwise defective.

Bob Axtell

March 30, 2005. Statement on our PIC Programmers

The PIC10FXXX series of PIC's do not work with the current DIY programmers.The correction is a firmware problem, and is not easily correctible.  While I DID find a problem with PIC10FXXX  in the CHIPINFO.CID, when I breadboarded the part, it still does NOT work. Bob Axtell. 
 
 

HISTORY
Microchip has recently been releasing PICs that use a very complex set of programming algorithms. Because the programming code is so lengthy, the DIY programmers no longer have enough space to contain every possible programming algorithm. DIY has decided to provide only the algorithms needed by the user. This allows MicroChip to make unique new algorithms and DIY programmers will be able to accommodate them.

UPDATES & STATUS
Due to the magnitude of changes required for DIY to redesign the firmware to accommodate future MicroChip releases, we have decided to temporarily "freeze in place" all firmware changes to DIY Programmers K150/K149, K128 and K182. This freeze is in effect until after the release of DIY K185, DIY's first production programmer. As soon as the K185 has been launched, we will then return to bringing older DIY programmers into the "strategies" fold. The freeze does NOT lockout changes made to the CHIPINFO.CID file, which may be published on the Forum. 

The new programmer will be the first to use the "Strategies" method, as outlined by suggestions earlier this month on the Forum. The K185 will be capable of instantly downloading a "strategy" not contained in its internal repertoire of "strategies". More about the K185 will be released next month.

STRATEGY DEFINED
A strategy is a method of programming that applies to specific group of PIC devices. For example, all of the PICs from PIC16F84A to the PIC16F628A, about 200 different PICs, operated with a single strategy. For the K150/K149, all of the serially-programmed PICs from the PIC16C54A to the PIC16C877 all used a single strategy, about 300 Pics. But the coverage drops with PIC18FXX39 because one strategy covers only the PIC18F2439/F2539/F4439/F4539 - a total of only 4 different PICs!

This method is devised as an answer to MicroChip's release of a plethora of complex programming algorithms. It will allow us the ability to accommodate ANY and ALL changes in the future, since we use ONLY what we need. 

FUTURE USES STRATEGIES METHOD
Future DIY programmers' firmware will- instead of trying to store every possible way of programming PIC chips- only store those that are relevant to the user. Since the older DIY programmers cannot NOT automatically upload instantly (it does not have the hardware to do so), we will encourage users to simply download relocatable ".o" files of each strategy so that they can "buildup" the PIC programmer firmware needed. The F628 will hold 4-5 strategies while the F648 chip can hold about 10 (every older programmer is able to accept PIC16F648 as well as PIC16F628 device as the programmer device). We do not have the manpower available to revise the firmware for all older programmers, update all new PICs, and bring online a major programmer at the same time.

NEW PROTOCOL & APPLICATION
Alas, there are so many changes that Protocol 18 cannot cover all of them, so the new K185 (and later, the revised DIY programmers) will use a protocol that fits the "strategies method" closely. MicroPro will be changed to reflect the new realities and might even have a name change. It WILL have an easy EASY way to install the USB drivers, etc and know it is running properly. The new protocol will be published as soon as it becomes stable.

FORUM SUPPORT
Will be maintained as before, as will the Technical Support Center in Tucson, AZ, USA. --Bob 

I am offering firmware programming services for DIY programmer owners. For $3 USD + shipping I will ship a programmed PIC16F648A for your programmer. The F648A is an enhanced 628A, and  can be used on ALL DIY programmers. The 648A will allow faster programming when Protocol 19 is released. 

There is no profit made here, it is done only as a convenience for DIY customers.
The shipping container absorbs whatever profit was made. 

Shipping is $1.50 USD for USA and territories, and normally $2.50 USD elsewhere in the world. Note: we cannot legally ship to some countries.

To obtain a programmed device, simply send money in USD funds to the paypal user ID of baxtell@comcast.net . You MUST include a valid mailing address, the HEX file needed, the PROTOCOL needed (normally 18 or the new 19), and an email address for advising shipment info. If you are in the USA, the total is $4.50 USD, elsewhere $5.50 USD. If you are unsure which file you need, simply identify the KIT number and we will automatically install the correct hex file for the protocol requested. REMINDER: when you use new firmware, you must install a MATCHING MicroPro.

--Bob  Axtell
Kitsrus Labs

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