rfPIC12F675K as Ebay Trigger Board Replacement

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rfPIC12F675K as Ebay Trigger Board Replacement

Postby seaton » Thu Oct 25, 2007 8:41 am

I've been investigating the rfPIC12F675K over the last couple of days and have come up with preliminary transmitter design based on Microchips appnotes (learning Eagle). This is targeted as a board replacement for the ebay trigger, however I'm in two minds on this chip.

Anyway the schematic can be found here
http://blog.everythingrobotics.com/wp-content/uploads/2007/10/strobejnr.pdf

Pros:
- Can run in FSK or ASK (schem: I have it running in FSK)
- Minimal component count.

Cons:
- Transmitter only.
- We would probably need to use their Receiver chip, but from the spec sheet there is a lot of additional discrete components that are required for the receiver. (I'm no radio Engineer, but I'm sure you guys could comment) then we still need a processor after the receiver.
- The Tx and Rx would need to be tuned.

I'm starting to lean towards a non RF Pic Chip with enough I/O and some flash memory for easy upgrades (i.e. no RF) and a seperate RF module, such as these http://www.hoperf.com/rf_fsk.asp that could be used in both senarios, i.e. ebay trigger replacement using PIC and a Pocket wizard replacement using ARM7, just the processors would be different, but the wireless modules are the same.

Also they have different wireless modules covering different bands that are pin compatible so they could be a drop in replacement.
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rfPIC chip

Postby sirket » Thu Oct 25, 2007 8:18 pm

The more I read about the rfPIC the more I both like and hate it.

Since it's looking more and more like we should use a separate transmitter and receiver chipset it seems to make less and less sense to use the rfPIC. And if you're not going to use an rfPIC it doesn't make sense to use a PIC at all. No one wants to program in assembly or pay for an expensive C compiler or have such limited IO and performance. We might as well just use an ARM 7 based chip (LPC2368 or equivalent). That would give us more flexibility to interface to an LCD screen or other functionality. The chip is small enough, has plenty of power, low component count, a LOT more memory, and can be programmed with GCC.
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Postby seaton » Fri Oct 26, 2007 7:43 am

I feel that for the existing ebay triggers (and there is a lot out there) a retrofit board to swap out the guts of the transmitters and receivers would be something that we could get out there real fast, and most people could do themselves. These tranceiver boards will initially be very dumb (just like the ebay triggers) except they will be more reliable. i.e. camera fires, stobe fires, nothing more nothing less, just that it does it every time, and cheaply. I've found a chinese manufacturer of some wireless modules that looks promising, and have ordered some samples (see this thread http://forums.everythingrobotics.com/viewtopic.php?t=63 ).

I'm still very keen on a hackable trigger and still in the process of an initial design, based on sparkfuns LPC-H2148 development board, and the circuit that was posted here http://forums.everythingrobotics.com/viewtopic.php?t=58 for the SAM7X. early stages at the moment. I will post my eagle files in SVN shortly so anyone can access and use them.
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Postby sirket » Sun Oct 28, 2007 6:12 am

Sounds good (re the eagle files in SVN).

I am waiting on a new oscilloscope to start testing some things for this project but I've just had an awful experience.

I decided to give the Instek GDS-2204 a try- 200MHz DSO with 4 channels. 25k point memory, TFT screen, reasonable price. Big mistake.

I wish I had been able to read some reviews or opinions about Instek before I bought. I've posted about my experience with Insteak over at the Make Magazine forums:
http://forums.makezine.com/comments.php?DiscussionID=2429.

The experience can be summed up as receiving a defective scope- being told I would need to send it back for repair which would mean being without the scope for 3 weeks, and then being told "I don't care" by the company's representative when I said that's not acceptable for equipment like this.
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Postby seaton » Mon Oct 29, 2007 6:38 am

sirket wrote:Sounds good (re the eagle files in SVN).

I am waiting on a new oscilloscope to start testing some things for this project but I've just had an awful experience.

I decided to give the Instek GDS-2204 a try- 200MHz DSO with 4 channels. 25k point memory, TFT screen, reasonable price. Big mistake.

I wish I had been able to read some reviews or opinions about Instek before I bought. I've posted about my experience with Insteak over at the Make Magazine forums:
http://forums.makezine.com/comments.php?DiscussionID=2429.

The experience can be summed up as receiving a defective scope- being told I would need to send it back for repair which would mean being without the scope for 3 weeks, and then being told "I don't care" by the company's representative when I said that's not acceptable for equipment like this.


bugger
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