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Topics - beth

1
Project development, ideas, and suggestions / Another ICSP pogo pin connector.
Hi all! How's everything going?

Here you are another/clone/copy/version of a pogo pin connector for Microchip microcontrollers ICSP. After struggling for a solution, I came across with the same idea as: http://http://www.pcbheaven.com/userpages/PIC_ICSP_Instant_SMD_Connector_with_Pogo_Pins/, so basically is a copy of it (thanks Giorgos, I've modified your design a bit).

You can find plenty solutions for the same problem out there, however I think that DP has the most extensive one ;):

The coolest for me is the Staggered one, however at the time I saw it I already had designed and sent mine to SeedStudio,in addition I don't know if this kind of connector is easy to source.

Here are the specs/characteristics of the connector:

  • It uses 0.68mm pogo pins in order to have a small footprint on the pcb. After seeing the new ICSP connector IAN is testing a double row design maybe could be better. To be exact I'm using pogo pins with that description "P50-B1 Dia 0.68mm Length 16mm 75g Spring Test Probe Pogo Pin" ;) (10 $2.49 at ebay), at the same time I ordered P50-Q1, but I've not tried them. The P50-B1 has has a tip of 0.48mm so it's perfect for 0.05" spacing (1.27mm). A drill hole of 0.7 its perfect for that pogo pin.
  • Among the 5 needed signals needed for the ICSP there are two additional pogo pins at both sides for alignment. In the designed eagle part this pins are holes instead of vias.
  • As you can imagine I'm attaching schematic and board designed in Eagle, I want to move to KiCad, but I'm a true believer on procrastination (aka laziness ;)).

In the end I decided to use two pcbs to make the pogo pins more stable and straight, using as you can see in the pictures two pc case screws (I don't have any kind of spacer over here).I was lucky because I left in the board a series of 3.2mm mounting holes, eventually letting me use this screws to space the boards nicely.

To solder the pogo pins at the same height I used a third hand tool that maintained the boards horizontally respect the table.

One thing to take into account, as you can see in the attached pictures I started to solder all the pogo pins, realising later that the sides ones were at the same height, grrrrr, they were suppose to work as guides, so they must be longer, thanks to the help of a beautiful extra hand (thanks to Mar) I managed to heat both ends of this pins to make them longer.

And that's all, just another icsp pogo pin connector ;). Thanks for reading and feel free to use it.

P.D.: Yes I forgot something I experienced a little nuisance while designin the vias for the pogo pins. In Eagle I set the drilling to 0.7mm and the pad size seemed fine, however when I placed the part on the pcb and tried the DRC I had overlap errors in all of them, because it seems that the DRC rules in the Restring values made the pads bigger. Using 1mm in the pad values of the Restring section of the DRC fixed the problem (I'm not a Eagle master so I don't know what I'm saying ;) )

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2
Bus Pirate Support / Some little PWM improvements (in pyBusPirate)
Hi to everyone here, How are you?, wanting to go to Tokyo :D :D?.

I have done a little contribution to the source code of the BusPirate python library related with the PWM. I need to make an arbitrary square wave generator so instead of programming a custom firmware for a microcontroller I thought that using the BusPirate and it's scripting capabilities was more interesting ...
 
I have just commited on the source code of the BusPirate repository two functions. Both on the pyBusPirate/BitBang.py related to the PWM, set_1khz_pwm_frequency as the BusPirate firmware/serial shell does, and set_pwm_frequency for setting the PWM to an arbitrary frequency.

I had test the set_pwm_frequency for setting successfully from 1Hz to 5333333Hz (or 5.33Mhz, cool limit number), look the attached pictures from the logicsniffer with 1Hz, 5.0Mhz and 5.33Mhz frequencies.

Also I have added to the repository the file FrequencySweeper.py that sweeps the PWM frequency in an interval (set via command line parameters). I need it to repair a car ecu, maybe it's useless for other tasks ;).

That's all friends, have a nice Christmas time ...

Kind regards, beth.

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3
Bus Pirate Support / 93C86
Hi everyone here (again), I had a new question for some pirate soul ;).

The last week I was repairing a circuit board and in order to get it working I need to read and write a 93C86 serial eeprom.

I had read some datasheets: http://www.atmel.com/atmel/acrobat/doc1237.pdf and http://ww1.microchip.com/downloads/en/devicedoc/21132e.pdf and it seems to use a 3 wire serial protocol, the protocol is not difficult to understand and I think that is not very difficult to implement.

Before to try to add such protocol to the bus pirate, I wish to know if it is already implemented on it, I think that is some kind of SPI in combination with a ChipSelect CS wire (a rising edge on CS and DI is the start bit), also it have a dual data width: 8bits or 16bits depending if the ORG ping is tied to VCC or GND/unconnected ..., well I didn't read the full datasheet and before to go in depth with it, I want to know if the bus pirate already support this kind of protocol.

That's it, thanks for your kind support
4
Bus Pirate Support / Could it be possible?
Hi everyone here!!

It's nice to talk to you ;)

I have a question about one chip I am planning to use (I'm waiting for the pre-order 5) with the buspirate.

It is a M68HC12, and as you can see on this reference manual http://www.freescale.com/files/microcontrollers/doc/ref_manual/CPU12RM.pdf, it have a "Background Debug Mode" or BDM function that allows developers debug the application and read eeprom memory.

It uses a propietary 1 Wire protocol described on pages 293 and further on the manual, and I am asking myself (and you) if the buspirate will have enough speed to handle such protocol, taking in consideration that the clock of the target application is 8 or 16 Mhz. (Look pages 295,296&297 on reference manual). I wish to know that in order to wait for the buspirate or start findind a device programmer specific for that kind of chips.

That's all, thanks in advance for your kind support.

Best regards, beth.

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