Bootloader for 16f87/88 that doesn't use UART

[bcd]

I have a board with a 16f87 that has a two way PC connection that is bit banged, with the HW UART used to transmit a high speed one way signal to some other equipment.

What I would like to do is add a bootloader to simlify reloading or updating firmware.

I've done a quick search and it seems all the usual suspects need to use the HW UART for bootloader activity. I saw a thread a while back about the SparkFun bloader being able to use any pin, but it seems its not so.

So has anyone seen a bl for a 16f87 that allows the use of a software uart ?? What would be great is one written in pbp, as it would be easy to maintain and make changes to led flashing when in boot mode etc.

with thanks,

bill

[mister_e]

Sure it exist or at least it could be done... as long as you're aware and you agree that the bootloader firmware will be way bigger and you're not code limited...

But... why you don't want to use the hw USART?

I saw once a 1 pin bootloader, and didn't used the HW USART, Wloader if my memory serves me well.

There's also that one using MCLR pin... omg, what was it's name... ZPBL or ZPL.

what i suggest is to look at TinyBootloader page, there's few suggestions over there.

[bcd]

Hi Steve,

Code space is not an issue. I cannot use the hw uart as I need it to generate rs485 at 250Kbaud ! On the PCBs it is wired as TX only, but even so I have not seen a half-duplex bootloader (please correct me, anyone..)

I looked at TinyBootloader earlier, but again it is tied to HW UART pins.

I'll keep looking. I found a mention on the Spark Fun site that bloader 1.6 could handle the 16f819, which doesn't have a uart. Maybe a bit iof creative code work is required...

bill

[dhouston]

Scroll to the bottom of the TinyBootloader main page and there's a list, with links, of other bootloaders, including ZPL and WLoader, which do not use the UART.

[ardhuru]

Very early on, Tony Nixon used to have just such a bootloader, RomZap. Not only could it use any pin, it also had an option to invert (or not) the signal, making it ideal for direct connection to the serial port. To my knowledge, development on this stopped a while ago, so I'm not sure about the support for 16F87. In case you are interested, I could mail you a copy, since Tony had kept it free.

Regards,

Anand

[victorf57]

Melabs had their meloader no longer sold perhaps if you call them they'll sell you one.(it's a great piece of software)
also basicmicro sells their programmer you can build a loader within their programming software
for any pin.( at least it use to be this way but you may want to take a peek)

Victor

[bcd]

Found a couple of options:
WLOADER - http://www.voti.nl/wloader/index_1.html
this allows any pin to be used and can work with a single pin. SRC code is in ASM with a command line Windows option (with Source in Delphi) or a Wiindows based app in Python.

PIC_E - http://www.ehl.cz/pic/pic_e.htm
Uses hardware UART, but has nice Delphi front end for PC and source code for PIC in ASM.

I am now looking at re-writing the PIC_E firmware using PBP to make it work with out the UART for my specific PIC.

These two don't have 16F87/88 definitions, but looking at the source it shouldn't be too hard to add the required info.

I might also look into RomZap - I remember reading about it a few years ago when I first toyed with the idea. Anand, if you have a copy could you email it or PM me.

If I get it going I'll upload it here.

Bill

[bcd]

ROMzap - http://piclist.com/images/com/bubble...mo/ROMzap.html

Looks pretty advanced for what I need - it seems to use UART, although it does support the 16F872 which doesn't have a UART.

I am downloading it now and will dig in to the Source files (if they are in the ZIP) to see how customisable it will be.

So has anyone ever written a bootloader in PBP??

bill.

[victorf57]

Take a look at this code maybe it will help.
http://www.oshonsoft.com/picbootloader.html
victor

[bcd]

Hi Victor,

Fantastic ! That gives me a good starting point. The PC applicatin looks a lot like the PIC_E one.

Looks like I am going to spend Sunday in the shed learning how to bootload !!

With Thanks,
Bill.

[ardhuru]

ROMzap - http://piclist.com/images/com/bubble...mo/ROMzap.html

Looks pretty advanced for what I need - it seems to use UART, although it does support the 16F872 which doesn't have a UART.

I am downloading it now and will dig in to the Source files (if they are in the ZIP) to see how customisable it will be.

bill.

Yes, the interface does look a bit complex first, but thats because its so configurable. Once you figure out the things you need, its a breeze to use. No it doesnt use the UART; you could use any pin for the bit banging.

Pity it only supports the 16F8XX chips, though; if you are able to adapt it for others, I would love to hear about it too... it was my preferred bootloader for a long time, till I had to switch over to the one from Mecanique. I still miss the flexibility and the option of not having to use a level shifter.

Regards,

Anand

[dhouston]

So has anyone ever written a bootloader in PBP??

See http://www.picbasic.co.uk/forum/showthread.php?t=4498

[dhouston]

If I get it going I'll upload it here.

That would be great. I have several applications where I'd like to use a 16F88 with a bootloader well enough documented for me to write Windows/Linux/Mac interfaces (using PureBasic) but the bootloader, itself, is beyond my skill level.

[bcd]

After a weekend in the shed I have learned more about the memory layout and programming requirements of the 16f87/88 then I think I ever wanted to know.

Darrel Taylor - Excellent piece of advice re the ERASE / Write cycle. I am investigating the best way to do this, as well as making sure we don't overwrite the bootloader at the high end.

dhouston - Thank you for the link to the thread on the 18F bootloader. There is some great info on reorganising the libary to get round some jumps to 0 that I had been seeing in some hex code I created.

There is so much to learn and so much more playing to do. Stand by everyone - its coming ! We are at 650 words, but I am trying some tricks to squish that down as there are other things I would like to add.

bill.

[dhouston]

There is so much to learn and so much more playing to do. Stand by everyone - its coming ! We are at 650 words, but I am trying some tricks to squish that down as there are other things I would like to add.

Once you post what you have, Darrel Taylor and Bruce Reynolds likely to suggest further improvements.