Connecting the propeller usb platform to the digital I/O board: A sad failure
varnon
Posts: 184
Hi guys.
Hopefully this will be a really obvious problem to someone who is more experienced.
I want to connect the gadget gangster usb platform to the parallax digital I/O board. I tried what I thought was reasonable, and I fried my propeller.
I am using the parallel connection. The serial connection sounds nice, but I want to start with the parallel so I don't have to rewrite a bunch of objects. I put together the I/O board (I would love a preassembled version) and did some testing. Everything worked fine. After testing with a ribbon cable, bread board and a whole bunch of jumper cables, I began considering a way to attach the propeller without cables. (There are way to many cables in my lab.)
The solution I found was to attach a 2x10 female header to the bottom of a circuit board, attach other pin headers to allow the propeller platform to attach to this, then wire the connections. Incidentally, the protoplus ended up being a great fit for this.
The 2x10 header connected nicely to the N and R rows. These rows aren't connected to each other, but are each connected to a neighboring row, giving me some space to plug in cables. I installed female pin headers on the top, and male pin headers on the bottom of the gadget gangster module for connection. The video and audio ports didn't fit in-between the protoplus and propeller modules like I wanted, but fortunately they did fit upside-down on the bottom of the protoplus.
Now I began connecting the wires, one by one, as I had done during testing with the ribbon cable and bread board.
First, I connected VSS on the I/O board to GND on the protoplus/propeller. Next I connected V+ on the I/O board to Vin on the propeller. According to the I/O board manual, this allows the propeller to be powered though the I/O board. (It seems the jumper needs to be on the pins above the 2x10 header. The manual is a little unclear on this.)
I tested this, no problems. The propeller took power from the I/O board. (Sadly, the on/off switch on the propeller does not turn it off when it is powered through Vin.) After testing with free wires, I soldered in the connections and tested again. Everything worked.
Next I connected VDD on the I/O board to V33 on the propeller. The I/O board needs this for logic power. Although the manual states 3.3 V or 5 V will work, previous testing showed that it only worked with 3.3v. I made the connections and then I started having problems. I don't remember if I had problems before soldering the connections in or not.
Once the propeller was attached to the I/O board, first the propeller received power, then ALL the relays and associated LEDs came on. Then, starting with relay 8, the LED became dimmer and the relays started turning off. Of course I disconnected the power as soon as I could, but by then it was too late. The propeller was fried. Fortunately it looks like the I/O board is okay. Applying three volts to the individual relay pins still activates the relays.
I realized something else while typing this. Since the audio/video ports are upside down, the audio port touches the I/O board. And it looks like it touches right where some circuit tracks are. I thought it was bare in that spot. (I put this together at home, and the lighting is terrible here.) I'm not sure this would be the issue, since only the casing of the audio port touches the tracks, and no pins were connected to anything yet.
Any ideas where I went wrong here? What should I do to connect everything?
I have a voltmeter at work, so I can check anything I need to check tomorrow.... but I'm not sure where to start. Any thoughts would be greatly appreciated. I love the propeller, and I get a lot of use out of it in my lab, but I am NOT an electrical engineer. I just want to have this done and move on with my work.
For reference:
http://www.gadgetgangster.com/find-a-project/56.html?projectnum=257
http://www.parallax.com/Store/Accessories/Hardware/tabid/162/ProductID/658/List/0/Default.aspx?SortField=ProductName,ProductName
http://www.gadgetgangster.com/find-a-project/56.html?projectnum=254
Hopefully this will be a really obvious problem to someone who is more experienced.
I want to connect the gadget gangster usb platform to the parallax digital I/O board. I tried what I thought was reasonable, and I fried my propeller.
I am using the parallel connection. The serial connection sounds nice, but I want to start with the parallel so I don't have to rewrite a bunch of objects. I put together the I/O board (I would love a preassembled version) and did some testing. Everything worked fine. After testing with a ribbon cable, bread board and a whole bunch of jumper cables, I began considering a way to attach the propeller without cables. (There are way to many cables in my lab.)
The solution I found was to attach a 2x10 female header to the bottom of a circuit board, attach other pin headers to allow the propeller platform to attach to this, then wire the connections. Incidentally, the protoplus ended up being a great fit for this.
The 2x10 header connected nicely to the N and R rows. These rows aren't connected to each other, but are each connected to a neighboring row, giving me some space to plug in cables. I installed female pin headers on the top, and male pin headers on the bottom of the gadget gangster module for connection. The video and audio ports didn't fit in-between the protoplus and propeller modules like I wanted, but fortunately they did fit upside-down on the bottom of the protoplus.
Now I began connecting the wires, one by one, as I had done during testing with the ribbon cable and bread board.
First, I connected VSS on the I/O board to GND on the protoplus/propeller. Next I connected V+ on the I/O board to Vin on the propeller. According to the I/O board manual, this allows the propeller to be powered though the I/O board. (It seems the jumper needs to be on the pins above the 2x10 header. The manual is a little unclear on this.)
I tested this, no problems. The propeller took power from the I/O board. (Sadly, the on/off switch on the propeller does not turn it off when it is powered through Vin.) After testing with free wires, I soldered in the connections and tested again. Everything worked.
Next I connected VDD on the I/O board to V33 on the propeller. The I/O board needs this for logic power. Although the manual states 3.3 V or 5 V will work, previous testing showed that it only worked with 3.3v. I made the connections and then I started having problems. I don't remember if I had problems before soldering the connections in or not.
Once the propeller was attached to the I/O board, first the propeller received power, then ALL the relays and associated LEDs came on. Then, starting with relay 8, the LED became dimmer and the relays started turning off. Of course I disconnected the power as soon as I could, but by then it was too late. The propeller was fried. Fortunately it looks like the I/O board is okay. Applying three volts to the individual relay pins still activates the relays.
I realized something else while typing this. Since the audio/video ports are upside down, the audio port touches the I/O board. And it looks like it touches right where some circuit tracks are. I thought it was bare in that spot. (I put this together at home, and the lighting is terrible here.) I'm not sure this would be the issue, since only the casing of the audio port touches the tracks, and no pins were connected to anything yet.
Any ideas where I went wrong here? What should I do to connect everything?
I have a voltmeter at work, so I can check anything I need to check tomorrow.... but I'm not sure where to start. Any thoughts would be greatly appreciated. I love the propeller, and I get a lot of use out of it in my lab, but I am NOT an electrical engineer. I just want to have this done and move on with my work.
For reference:
http://www.gadgetgangster.com/find-a-project/56.html?projectnum=257
http://www.parallax.com/Store/Accessories/Hardware/tabid/162/ProductID/658/List/0/Default.aspx?SortField=ProductName,ProductName
http://www.gadgetgangster.com/find-a-project/56.html?projectnum=254
Comments
I'll second Circuitsoft's suggestion of taking a couple of pictures. I think you explained how things are connected well but I found myself losing my place as to which wire is connected where.
I've fried my share of Propeller chips (I might hold the record for number of Propellers killed). A forum member, Leon, recommended ChipQuik for removing surface mount ships. I've found ChipQuik is as useful as Leon claims. The low temperature melting point keeps the PCB traces from being damaged.
I'd also suggest picking up an inexpensive multimeter so you can check connections at home.
The Vin is frequently used for servos and other devices being controlled by the Propeller. When used to output power the switch will turn it on and off but when used to power the board it's on the wrong side of the switch for the switch to be useful. I think most people use Vin as an output.
I was using a shielded cable to connect a video camera to a pair of Propeller boards stacked on top of one another. The problem was, the shielding was uninsulated wire mesh around three inner wires. It wasn't untill the wire mesh killed the Props on both boards that it occurred to me I had bare metal laying across a whole bunch solder joints.
Sometimes one (or I should say "I") can become so engrossed in solving one problem that a giant problem can waltz on by without being noticed until too late.
You can see the bottom of the protoplus with the header attached. The wires connect the header to Vin, V33 and GND.
The next picture shows the protoplus and the header on the I/O board. (The male header was removed when this picture was taken, more on that in a bit.) Here you can see how the I/O board ultimately connects to the propeller. To reiterate from I/O board to propeller: V+ to VIN, VDD to V33, and VSS to GND.
The final picture shows the whole contraption.
This is the section of the I/O board manual that led to me to these connections.
Given this information do my connections at least seem to make sense?
I did consider one other possibility. If the connection between the protoplus and the I/O board was misaligned... bad things could happen. It is easy to do considering the connections are on the bottom of one board. (See the third picture.) If I accidentally set the protoplus down one set of pins to the left the V+ on the I/O board would be connected to V33 of the propeller. I think this might have been what happened. 12 volts would have rushed in through V33 and fried the propeller. (Am I right? This sounds like a good way to kill the propeller.) I would not have known this happened if I removed the propeller immediately. This is the only thing I can think might have happened.
For this reason I removed the pin headers from the I/O board and will replace it with a shrouded header to this pins cannot be misaligned.
I think my first problem was a failure on my part to understand how the VIN pin is set up on the Gadget Gangster platform. I previously thought the VIN ran through the same voltage regulator that the barrel jack or power terminal plug went through... but now I'm not so sure that it does. Maybe providing 12v from the daughter board into VIN does not run the power through the regulator circuits. I can't really find a good written answer, but this is my current assumption.
I'll just power the propeller separately.
I'm having another problem now though. I did not have this problem during the initial testing.
When the propeller is attached to the i/o board, all outputs on the i/o board are always activated, regardless of the program on the propeller.
Some testing has shown that if V33 on the propeller is disconnected from VDD, the outputs work as they should. However, the inputs need this connection to function. Everything worked during bread board tests, so I am not sure what is going on. I have this error anytime 3.3v is connected to VDD, regardless of how it is connected (ie, from the propeller, from a battery, from propeller through the protoplus). I cannot find any bad joints or anything that would physically indicate any problems. I got a better digital multimeter and brought it home, so I can test whatever I need... But I have no idea what to test. Any suggestions?
I would love to be able to swap one part and have things work. I do NOT want to build another one from scratch. I don't mind the price, but it takes more time than I would like, my hands aren't as stead as I would like and my color vision is just bad enough that it takes me forever to identify the correct resistor. Its just a huge pain in the ***. (Anybody ever see one of these for sale pre-assembled?)
Anyone have any thoughts?
PS, my new gadget gangster platform is red!
I obviously did not understand the flow of current in VIN. I thought it went to the voltage regulator in the USB module, but it does not. 12v of course will fry the propeller. I believe this somehow also leads to some part in the daughter board being fried.
With a new propeller, and a new daughter board I rebuilt everything. They are powered from the same power supply, but from two different barreljacks. It isn't pretty, but it does have my requirement of less cables everywhere. I also installed the pin header connecting the daughter board to the propeller at an angle to give the audio and video ports on the propeller plus a little more clearance. Unfortunately, I did not find a shrouded header that fit the dimensions I wanted. The one I ordered only restricted two sides, the other two sides were open enough to allow the pins to be miss placed.I did see some shrouded headers that completely restricted the connection, but I could not order those in small numbers. Of course, after all of this, the gadget gangster module has been discontinued, so this thread may not be of use to anyone else, but I wanted to provide an update anyway. I may buy a few spare gadget gangster USB and protopluses.