PPLA Module - Propeller Platform Logic Analyzer - now available
Brian Riley
Posts: 626
This is a BSLA-like unit. It inserts into a Propeller Platform setup between the processor board and its associated application boards. Using 'stacking headers' on the PPLA, it presents no connection problems. The PPLA is then connected to a host computer which must run Win XP or better and have .Net 2.0 or better. Jazzed is working on upgrades to the host software. Source code will be available under MIT license.
The PPLA runs at 100 MHz and is capable of 10 nanosecond sampling. It samples P0 to P27 and can be configured to do 2 more channels (P28/P29 or P30/P31) bringing the total to 30. All the details are at the webpage
http://www.wulfden.org/TheShoppe/prop/ppla/index.shtml
The introductory price is $36. Which, by the way, is a lot less than what the BSLA sold for at End-of-Life!
I enclosed two pictures, One is the PCB sans chips, crystal and stacking headers, to give a better view of the layout and parts. The second is the complete unit showing how it neatly stacks between a PP-USB and a VGA-AV platform module.
The PPLA runs at 100 MHz and is capable of 10 nanosecond sampling. It samples P0 to P27 and can be configured to do 2 more channels (P28/P29 or P30/P31) bringing the total to 30. All the details are at the webpage
http://www.wulfden.org/TheShoppe/prop/ppla/index.shtml
The introductory price is $36. Which, by the way, is a lot less than what the BSLA sold for at End-of-Life!
I enclosed two pictures, One is the PCB sans chips, crystal and stacking headers, to give a better view of the layout and parts. The second is the complete unit showing how it neatly stacks between a PP-USB and a VGA-AV platform module.
800 x 600 - 128K
800 x 600 - 100K
Comments
TrapperBob
OBC
YES!!!!! I never even considered not using stackable headers. Use of stackable headers means the PPLA slips in wherever your PP processor board is in the stack with no cause to have to worry about which gender and row position connectors you have. Since most PP processor boards have socket headers in the outer rows, which is the configuration I showed on my PPLA web page, BUT, there is nothing to stop anyone from doing it differently.
Now, as anyone who has worked with stacking headers can attest, they CAN BE a royal PITA to align and solder! I include with the kit a set of 20 pin long headers to use to align and solder.
- insert stacking headers into holes in PPLA PCB
- insert long double male headers into socket part of stacking headers
- flip PPLA PCB over carefully and mate the second side of the double male headers to the socket headers on a PP processor board
- you now have the pins aligned and the board upside down with gravity holding it flush to the stackin headers
- solder the four corners to start
- not exactly 'simple,' but far from difficult.
If you would provide an item # and price for just stackable headers, I'd love to buy a few sets from you. Stackable headers are the way to go with any GG addon board. (I'd love to order them with my PPLA kit, if you'll do it.)
OBC
I'll be working on Propalyzer again soon to provide enhancements and make it MIT open source. Another software item is in the Propeller code. I plan to make the 100MHz sample rate buffer deeper. One feature which I need is "Save to Trigger" so that's in the plan. Other things are coming later. Longer term a Qt version of Propalyzer will be developed.
Nick should also be offering Stackable Headers soon.
These are commonly used in the Arduino community. You can pick them up from www.sparkfun.com or www.adafruit.com. Sometimes they come in complete Arduino-compatible sets, sometimes individually.
Here are individual 8-pin headers (not sold in the usual Arduino 2x6 + 2x8 pack):
http://www.sparkfun.com/products/9279
They are nowhere near as cheap as they probably should be, but I haven't come across similar headers very many other places.
As Brian said, they can be a pain to work with sometimes. In addition to needing to line them up correctly to solder (and I usually do what Brian shows in his pictures), sometimes you need to shave a little of the housing off to have them fit well next to each other.
By the way, I also ordered a couple of the PPLAs yesterday. Coincidentally, I think Brian lives about 10 miles away from my brother but I figured it was easier to have them shipped to me than to have my brother track down Brian
http://forums.parallax.com/showthread.php?127144-Propeller-Platform-Logic-Analyzer-Module
For the connection, I will probably use a cable from FTDI that has the USB/TTL circuit built into it with the header rearranged for the correct pinout.
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=768-1015-ND
For something like this, once the Prop (EEPROM) has been programmed I usually don't want the PC to be able to reset the Prop. That's one of the reasons I like these cables - I don't have to connect anything to the reset pin.
That being said, I think you may need to add a little hardware to use this cable to reset the Prop (if the correct signal is available at the header). I usually use a Prop Plug for programming/debugging and one of these cables (or something similar) for a "final" product.
Even with the drop in prices adding a USB/FTDI chip,, dealing with surface mount, etc. overall adds $10-$20 to the selling price of a board. I wanted to make the PPLA inexpensive enough to be considered by anyone. The USB adapter that I sell, Modern Device's BUB, for $14 was designed for Arduino, but when you realign the pin out to Prop Plug order no one in the lashup has any idea its not talking to a gen-u-wine Prop Plug!
Most people have a Prop Plug or a SerPlug or one of my P1's or BUBs. Why keep buying FTDI chips over and over when they are going to spend 75% or more of YOUR time doing nothing? ON my bench I have 2 BUBs, a Prop Plug, an old FTDI cable, and 2 P1's for Arduino and Prop work. One BUB is hard wired for Prop, the other for Arduino, it can be used with a small adapter for Prop, the P1's work through USB/RS232 adapters. The FTDI cable is Arduino 5 volt, but I made a pin out adapter with a 1K resistor in the TX line and it will do Prop if need be. I am doing all this with BST on an iMac under MacOSX and occasionally under WinXP via Bootcamp. I have at least 17 or 18 different Prop boards and only 5 of them have USB the rest are serviced by my array of adapters. I have done high speed data collection for long periods on Props and Arduinos using the adapters and so far haven't been torpedoed.
The short answer, David, is, unless people simply won't buy the PPLA because of this, NO, I have no plans for a USB port.
The PPLA has a Reset Enable jumper, remove the jumper and Reset is isolated. It also has a Write Enable jumper, if removed the EEPROM is Write Protected.
The Reset Enable will be most handy if you chose the option to remove the EEPROM and freeup P28/P29 to give you 30 channels. Load to RAM w/o EEPROM is most vulnerable. Load to RAM with Reset Enable, then pull the jumper.
I guess I was speaking in more general terms and not really addressing this board specifically. I really like/appreciate the jumpers that you've included in this board.
Why take out a $30 Prop Plug, I can sell you a $14 BUB with no connector that could be more readily hooked up!
The FTDI cable does not have a DTR connection, but it does have RTS.
A program could be used to download with RTS for reset instead of DTR.
I knew it was something like that. I have to admit that I was too lazy to look it up.
I have posted a "BUILD" page. It's linked from the main PPLA page. I also have a stub for a How To USE page, which will be worked on over the weekend.
http://obex.parallax.com/objects/554/
Hanno
As far as I know, the long-tail stackable headers are available in different sizes in wholesale quantities from 4uconnector.com. The page with single-row female headers with 10.5mm and 15.5mm long tails is:
http://www.4uconnector.com/online/itemagrid.asp?seriesdesp=2.54+FEMALE+HEADER+DIP+STRAIGHT+HEIGHT%3D8.5MM&seriesno=0118&GroupNo=01&groupdesp=Pin+%2F+Female+Header&itemnum=4953&sample=0&seriesnum=90&
I believe the stacking headers used on the Arduino boards are the ones with the 15.5mm tails. This site only has two sizes with that length tail: 6-pins (Item number 19874), and 8-pins (Item number 19875). I think the ones with 10.5mm tails would not be tall enough (unless you used two of them stacked to get enough height).
For the Propeller Platform modules, you need 2 x 4-pin and 2 x 16-pin, but they don't have 16-pin headers with any length long tails, so you'd have to use two 8-pin ones. The also don't have any 4-pin ones with 15.5mm tails, so you'd have to split an 8-pin one into two, or just cut off two pins from a 6-pin header.
I've misplaced my password for their site at the moment, but the order for each item is a minimum of 1000 pieces, and as I recall the price per piece (for the 6 and 8 pin versions) is about $0.10 each, or a minimum order of about US$100.00 per item number. That's a few more than I need at the moment.
I have some of the Arduino stacking headers from Sparkfun, and I use them on my PP boards. But believe me, it is very hard to split one 8-pin female header into two 4-pin ones without losing a pin. It just might be easier to sacrifice two pins from a 6-pin header.
@Ding Batty, do you have any of the 10.5mm tail parts on a set of boards?
If you do can you measure the actual stackup? Thanks a bunch.
OBC
I have a SDRAM board with the Arduino headers, and also a PP proto board with the same headers. I will measure this evening, (probably in a few hours -- it is Valentine's Day after all
I think the "Arduino" ones are the shorter ones. They may not be long enough for some Platform boards. But the longer ones will really space things apart a lot.
The rest of the headers discussion should go the other thread...