Replacing the FT245BL chip in the PIC Pgm USB programmer - Page 1
Forum section: electronics / general

author: IAmSaad
author_rank: Newbie
timestamp: August 17, 2016, 11:04:33 am
content: Hi i want to make my own PIC programmer because i am unable to afford the PICkit 3. I have to decided to make the PIC Pgm USB programmer but the main issue is the FT245BL chip. Its not available here and if it is available it costs like ~ 700 PKR ($ 7) - that makes the total cost go upto 1500 PKR ($ 15). Is there any cheap and highly available chip (which is used in multiple devices) that can replace the functionality of the chip. I know that it has something to do with converting the USB protocol. The chip can be replaced if i use the parallel port but that is not an option

author: Monkeh
author_rank: Super Contributor
timestamp: August 17, 2016, 12:46:22 pm
content: A clone of a PICKit 3 costs about $12. If you can't afford that, how can you afford chips to program?

author: IAmSaad
author_rank: Newbie
timestamp: August 17, 2016, 01:11:11 pm
content: Yes i can buy those but they don't usually last more than 1 week. I can buy the original picKIT 3 but the problem is that they are vastly overpriced as compared to the original price. The FT245 chip is making my homebrewed programmer costly thats the issue

author: Ian.M
author_rank: Super Contributor
timestamp: August 17, 2016, 02:36:17 pm
content: The USB PICPgm requires FDTI's bit-banging mode to work *PERFECTLY* - forget about clones or work-alike chips, they wont do the job in this demanding application. Also the PICPgm page says its horribly slow due to limitations of the USB bus, so I wouldn't build it on a bet!Build a PICkit 2 clone! That gets you over 700 devices with MPLAB X support for about 60% of them, many with debug support.If you cant get the use of a real programmer to program the PIC18F2550 it requires, use the PICPgm software with a JDM or parallel Tait Classic programmer or similar on an old PC with legacy ports running Vista or earlier for the inital firmware load.

author: IAmSaad
author_rank: Newbie
timestamp: August 17, 2016, 03:06:06 pm
content: Thanks Ian. I will follow your advice but can you point me to some schematics for PICkit 2 or 3?

author: Ian.M
author_rank: Super Contributor
timestamp: August 17, 2016, 03:46:15 pm
content: The schematics for both are in their user guides available from the Microchip site. Do a Google search for them (e.g.PICkit 2 User Guide) with the qualifiersfiletype:pdf site:microchip.com. The PICkit 2 is considerably simpler than a PICkit 3, and various cut-down versions exist e.g. leave out the Vpp boost circuit for LVP only (which unfortunately blocks debugging for PICs that use HV programming) , or leave out the Vdd control circuit for programming/debugging with target power only. The SPI EEPROMs are only needed for Programmer To Go mode.If you are trying to build a PICkit 3, you need an image of the firmware containing the bootloader. AFAIK this was never officially released, but it was leaked by a Microchip staffer in their forum thread "PicKit 3 and RS/AP upgrade" (post#53). Its rather old so you will need to force bootloader mode by holding down the button the first time you connect it to MPLAB or the standalone app to force an update. Sorry, no direct link because I don't want to give Dave any legal hassle.

author: stj
author_rank: Super Contributor
timestamp: August 17, 2016, 06:35:14 pm
content: the clone pickit3's are as good as the original - i have both.if you have a clone fail on you - specially if it's intermittant - it's 99% likely to be the usb cable they give with them.those cables seem to have some bad soldering in the plugs sometimes.

author: jesuscf
author_rank: Frequent Contributor
timestamp: August 18, 2016, 07:53:20 am
content: Quote from: Ian.M on August 17, 2016, 02:36:17 pmA few days ago I made a PIC32MX programmer using bit bang mode with an FTDI's FT230XS. It can load the Flash memory at about 900 bytes/second. Verifying the flash memory with it is a bit slower: about 580 bytes/second. Any idea on how does that compare with a PICkit 3 or other programmers for that matter?pro32 -p -v ..\xc32_stdio\serial.hexIDCode=0x6610053 : PIC32MX170F256BErasing flash memory.Loading Program Flash: ########################## Done (16128 bytes).Loading Boot Flash: ####### Done (896 bytes).Done 17024 bytes in 18.9 seconds. (900.4 bytes/sec)Verifying program flash: ########################## Done (16128 bytes).Verifying boot flash: ####### Done (896 bytes).Done verifying 17024 bytes in 29.3 seconds. (581.1 bytes/sec)

author: JPortici
author_rank: Super Contributor
timestamp: August 18, 2016, 10:59:51 am
content: Quote from: IAmSaad on August 17, 2016, 01:11:11 pmare you kidding?i have had a clone for at least 6 yearsi also have an original and when that one was busted long after the warranty was expired microchip only asked the address to ship a new one. several busted at work and each and every one of them was replaced for freeplus it's also a debuggerand in the long run it will be the best investment

author: Ian.M
author_rank: Super Contributor
timestamp: August 18, 2016, 12:44:44 pm
content: Even if you get the PIC24FJ256GB106 that is at the heart of the PICkit 3 as a free sample, build it on a protoboard you've already written off the cost of, and don't place any value at all on the time you will spend on it, its almost certainly going to be cheaper to buy a clone rather than try to build your own. Also, if you are knowlagable enough to build one, you should be ale to fix any faults that may develop on the clone, unless you do something crass like cross-connecting it to AC mains and burning it (and your PC) to crispy electronic ash.

author: IAmSaad
author_rank: Newbie
timestamp: August 18, 2016, 12:50:40 pm
content: @JPorticiNot all clones are created equalAlso Microchip doesn't have an office/distribution center here in Pakistan even though the PIC being very popular among students as well as the industry.And btw do the clones have a good debugger?@IanThanks for the valuable reply. At this point I'll either go for the PICkit 2 or 3 (clone ofc).

author: Ian.M
author_rank: Super Contributor
timestamp: August 18, 2016, 01:42:05 pm
content: If you are going to buy a clone you should probably get a PICkit 3,Many commercial PICkit 2 clones are rather dodgy. As I said earlier its possible to simplify the circuit but that will limit its capabilities and may cause reliability problems. As the PICkit 2 is the 'bargain basement' Microchip compatible programmer, there is a tendency for clone manufacturers to cut every corner they can in the design to keep the price down. The PICkit 3 clones tend to be better, and are generally fairly fully featured, though really cheap & nasty ones may omit the PTG EEPROMs and even the AUX/LVP pin on the ICSP connector.

author: JPortici
author_rank: Super Contributor
timestamp: August 18, 2016, 05:26:58 pm
content: Quote from: IAmSaad on August 18, 2016, 12:50:40 pmi supposed so (one of the reasons for your nick i'm sure)the rule years ago was to get those from sure electronics on ebay, i have no idea about now because, you know, it never broke(though i had to manually download the firmware a fuckton of times.. but that's because i was using it on a virtual machine and the usb driver on virtualbox is.. not good at all)one thing about the PK3 clones i've used and seen: they won't work under OSX ( > 10.6.or LINUX, but work just fine under any version of windows. I am not sure why but i think it is because they have no serial number, which is the only difference between clones and originals (hardware is exactly the same).the debugger in my clone works just as good as the original

author: stj
author_rank: Super Contributor
timestamp: August 18, 2016, 07:48:12 pm
content: my clone works in Linux using MPLABX just fine.i used 64bit debian - not that it should matteri'll admit i only use it as a programmer, but no recognition or useage problems here.

author: matkar
author_rank: Regular Contributor
timestamp: August 19, 2016, 08:29:19 pm
content: Regarding your original question;I don't know if it would work but a newer version of the FIFO chip is the FT240X. Its cheaper as well.On the other hand I have a PICkit 3 clone from Sure electronics as well and had no issues using it for the past few years.

author: dannyf
author_rank: Super Contributor
timestamp: August 19, 2016, 08:48:57 pm
content: QuoteThen you aren't using it the right way.

author: Ian.M
author_rank: Super Contributor
timestamp: August 19, 2016, 10:46:32 pm
content: You'll get no end of trouble if your target board's Vss rail isn't at the same potential as your PC's chassis. A bonding wire between them can prevent disasters, especially if you are working with high current DC motor drives or similar. A PICkit 3 is totally unsuitable for debugging any circuit that has a non-isolated mains PSU.Other ways to kill a PICkit 3 include ESD, hot-plugging its ICSP interface, not connecting the Target Vdd pin, applying a voltage source to the Vpp/MCLR pin without a series current limiting resistor, allowing Vdd on an externally powered target to go outside the range 0V - 5.3V, even transiently at switch-on, or disconnecting or powering down the USB interface while external Vdd is present. Often it will survive such abuse, but each time you do so, you risk killing it.

author: JPortici
author_rank: Super Contributor
timestamp: August 20, 2016, 12:11:42 am
content: Quote from: Ian.M on August 19, 2016, 10:46:32 pma good clone will survive all of that as much as a legit PK3 would

author: Ian.M
author_rank: Super Contributor
timestamp: August 20, 2016, 12:42:46 am
content: Quote from: JPortici on August 20, 2016, 12:11:42 amCertainly, but if the O.P. has been killing clones in a week or two, he's doing something wrong.I should clarify that by hot-plugging the ICSP interface, I mean connecting to a powered target or with target power already enabled. Its normal operation to plug in the ICSP connector with the PICkit 3 powered via its USB cable so long as the target isn't powered and the PICkit 3 Target Vdd supply isn't on.