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Topic: Dev version of the #twatch (Read 9506 times) previous topic - next topic

Dev version of the #twatch

Hi Ian,

I'm having a project in mind that requires heavy modification for the firmware of the twatch. So the reflashing limit (~100 times) is not good enough for me, as I will have to throw away a lot of my prototypes.

I would like to ask if you're having a dev version that allows more than 100 times of reflashing?


Re: Dev version of the #twatch

Reply #1
Yes, I used a 24FJ64GA002 version to develop the firmware: ... tch-v1v1b/

I believe the Eagle files are in SVN or the forum somewhere. Let me know if you can't find them, I probably have a copy somewhere.
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Re: Dev version of the #twatch

Reply #2
Couldn't find the term "programming cycles" in the PIC18F2550 datasheet. How many does this MCU have?   @.@

Re: Dev version of the #twatch

Reply #3
for the pic18f2550 it is on the third page; erase/write flash cycles 100.000 times, for the pic24 it is 10.000 times (also on page 3).

Re: Dev version of the #twatch

Reply #4
Got it. I needed to search for "cycle", not "cycles", or "x cycles".

Special Microcontroller Features:
• 100,000 Erase/Write Cycle Enhanced Flash
Program Memory Typical
• 1,000,000 Erase/Write Cycle Data EEPROM
Memory Typical
• Flash/Data EEPROM Retention: > 40 Years

Of course is not a special feature so the info is on page 11:

The PIC18F97J60 family provides ample room for
application code, from 64 Kbytes to 128 Kbytes of code
space. The Flash cells for program memory are rated
to last 100 erase/write cycles. Data retention without
refresh is conservatively estimated to be greater than
20 years.

Re: Dev version of the #twatch

Reply #5
I remember only the datahseet of the 18f97j60 doesn't mention the endurance on the first pages. I wonder why :D

Has someone an explanation why this chip has so little erase/write cycles?

Re: Dev version of the #twatch

Reply #6
I don;t know, and it's really poor choice because other chips (18F24J50) don't have quite as low limitations (10K+), and these are the only embeded ethernet chips. Maybe the ethernet gets so hot they have to use a different flash for reliability and it has fewer write cycles.
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Re: Dev version of the #twatch

Reply #7
The 3V MCHP Newsletter (April 2007) lists the PIC18F97J60 as having 1K writes (typ). The 2nd generation 18J series has 10K writes (min), but no ethernet specced chips fall into this category (yet anyway).

Re: Dev version of the #twatch

Reply #8
The topic has been raised before... here's MCHP's response (in 2006):

"Dear Microchip customers,
Thank you for bringing your concerns to our attention. As always we would like to help solve your application's requirements.
Regarding the particular issue noted here (ie 100 write cycles):

   1. Microchip's dsPIC products are offered in 2 families - dsPIC30F and dsPIC33F. While the dsPIC30F flash has a typical endurance of 1 Million E/W cycles, the dsPIC33F has a typical endurance of 1000 E/W cycles across -40 to +85C temperature. The difference is due to the different process technologies implemented on the two families.
   2. Microchip is actively characterizing the current dsPIC33F and PIC24H Flash Memory so as to provide our customers with improved E/W endurance and retention performance on these initial products
   3. We are fully committed to supporting applications that require 16-bit controllers. There will be future products which support enhancements to the Flash endurance specifications. We are fully aware of the difference in the specifications and strive to make product improvements to meet your needs.

For customers using products available today, we suggest the following options:

   1. Enurance at room temperature is typically much higher than the datasheet endurance and should not be a problem while debugging. If Flash endurance may be an issue during development and debugging please request more samples from . Samples are free.
   2. If Flash endurance beyond 1000 W/E cycles is required during application run-time, we suggest:
          * Use dsPIC30F products when you need high endurance internal Flash and EEPROM.
          * If using dsPIC33F products, cycle through a block of program Flash words so that you are writing a different word of program memory on each write cycle. This effectively increases the endurance. This applies to applications in need of internal EEPROM.
          * Using our line of serial EEPROMs that are available in space-saving 2x3 DFN or SOT packages. We offer both dsPIC33F and Serial EEPROMs at attractive costs.

Best Regards,
Microchip Technology Inc. "

Re: Dev version of the #twatch

Reply #9
Thanks suggestions -- However, I wasn't able to find the PCB for sale (or better yet, the assembled PCB for sale) on Seeed. Any chance I can have one of those?

Also, how "hard" it is to port the firmware written for the PIC 24FJ64GA002 + SOIC ENC28J60 to PIC 18F67J60 -- for example, how many LoC? Do I have to use a different IDE?

I'm all new to hardware (just have a little bit of experiences on coding), so sorry if my questions are dumb.

Re: Dev version of the #twatch

Reply #10
Sorry, v1 was never for sale on Seeed, and the PCBs are all gone. You'd need to make some new ones, or I can start an order with Seeed if there's enough interest.

It wasn't hard to port, just changing a few variable types and setting some defines, I've already done all that in the port in the #twatch code so there's not much to do. There is a different compiler for the 18F and 24F, same IDE though.

This design is pretty advanced, it'll be a huge jump from coding to working with hardware-level networking on a 16bit uC. If you're brand new to hardware you might consider something a little simpler, or just get a development kit and learn about the PIC hardware first.
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Re: Dev version of the #twatch

Reply #11
Olimex does sell a lot of PIC development boards, including some with a ethernet connection (either external chip or internal in PIC)

I think pic-web or pic-mini-web would suit you best. These have a pic that is 10k+ flashable instead of just 100 for the PIC18F97J60 (the onechip sollution)