Home of Cluso's MultiBladeProps
Single Board Computer using multiple Parallax Propeller Microprocessor chips
TriBladeProp SBC PCB - Assembly Instructions & FAQ
Q: Is there an audio out somewhere I'm not seeing?
A: No - use Blade #3 with an external connection. Maybe there a Spin Studio Audio pcb? It may be possible to use the connector pins on SS1/SS2/J32 for soldering on a simple audio circuit.
Q: Can you give me a BOM list so I know exactly what to order. Some of these chips are a mystery.
A: I have posted a BOM (parts list with Digikey and Future Electronics part numbers). ALL parts can be obtained between these 2 sources. Not all parts will be required. I will detail (soon) a list of what parts I recommend. How to build the pcb in sections and test along the way (partially done below), including the two modifications required.
Q: It looks like I could skip the surface mount USB stuff and use a Propplug. Confirm?
A: The PropPlug section may be skipped and use an external PropPlug - I did this first. Each Blade (Prop) has it's own PropPlug input connector. The microSD connector is SMT but is fairly easy to solder. I also suggest the regulators be SMT (TO252) as these are also easy to solder, but if in doubt fit TO220 through hole parts.
Q: How about some pictures of this constructed. It'll help me. :)
A: Already posted. Click the picture to zoom in once or save to Paint and zoom in.
How to build your boards...
Q: I note there are some components on the underside? How do I solder these?
A: Yes, there are some components on the underside of the pcb. I suggest you mount these before mounting the component above it on the top side. Mount the component and before soldering, trim (cut) the leads as close as possible to the pcb on the top side. Then solder the component on the top side. If you mount the underside components later, trim them as I mention and place them into the pcb and solder them on the underside. Note this will be difficult for the Resistor Network so make sure you do this before mounting the SRAM U24. On the photo I have not yet mounted any EEPROMs on the underside. Ensure you get the orientation of the component correct - they CANNOT be soldered on the topside as the pinout would be incorrect. (Underside components are shown on the overlay as dotted outlines)
Q: How do I solder the components? (I presume most of you will know this)
A: Solder the SMT components first. Then solder the low profile components next. Use a piece of foam to hold them in place and a breadboard (for cutting bread) or stiff cardboard to hold the foam and components in place. Turn the whole lot over keeping pressure between the breadboard and pcb - this will hold the components close to the pcb. Just solder (tack) one pin of each component (two diagonal corners on the ICs). Now turn the board over and ensure that the components are down tight to the board. If not heat the pin and push (careful not to burn yourself) the component down to the board (use a piece of cloth or something to protect yourself from burns).
Q: What options do I build?
A: Until I get a full description of the various options I suggest you email me.
Q: What should I get going first?
A1: First build the on-board PropPlug if you require it. Solder the SMT FT232RL U91 first. Be careful, this is a very fine SMT IC. If you don't know how to solder this either get someone else to do it or give this circuit a miss (you can use an external PropPlug). I found that I got bridges (shorts) between pins with the solder paste - I used solder wick to take off the extra solder causing the bridges. Do not overheat the IC. Next, solder R91, R92, R93, then U91, then C92, C93, then C91, then Q91 (WARNING - there is an error and the pins need to be bent/inserted differently to the overlay which is incorrect. See attached drawing/photo of this.) Lastly, push the J92 PropPlug connector carefully into the pcb - we do not really want to solder this until the other lower parts are soldered, but we have to be careful it doesn't come out of the pcb and short something. Once this is done - if you have another pcb that requires an external PropPlug you can test the PropPlug to it.
A2: Next, build the power supply. Solder in this order: Q1 & Q2 (if SMT), D4, C2, C3, SW1, J1 (2.1mm is the same as the PropProtoBoard), C1, then Q1 & Q2 (if t/hole). Check you are getting the +5V and +3V3 (means +3.3V) output -you can check at J3.
A3: Next get the Propellers you intend to use. Just solder the capacitors, resistors, PropPlug header, xtal and Propeller IC, and the LED circuit. You will note that each Blade (Prop circuit) uses identical style component IDs (e.g. the Prop IC is U11, U21, U31; xtal is X11, X21, X31). So what you need to get a minimal circuit running for each Blade is Cx1, Cx2, Rx1, Rx2, Jx1, Xx1, Ux1 (where "x" is 1, 2 or 3 for Blade #1, #2 or #3). This is a minimal circuit, without the EEPROM. Also solder the 3 LED test circuits (R1, R2, R2 and D1, D2, D3) - I used D1=Green, D2=Blue, D3=RED. Now you can check each Blade (Prop) by connecting to a PropPlug and downloading a program. I posted a program in one of the above posts to flash a LED - just connect one of the LEDx connection points to P24 (pin33) of the prop ( don't solder it - just carefully poke one end in the LEDx hole - it should flash when working correctly.
NOTE: If you are going to use 2 x SRAMs on Blade #2, it may be best to place a kynar wire cut to length under U21 soldered to the top of pin37 of the Prop chip. (Kynar wire is very thin modification wire with a teflon type coating ofter used for wire wrapping). Be careful to protect the other end from shorting with tape for now.
I will continue this later. Here are some things to consider..
- Blade #1: What options you will use. VGA and/or TV, Keyboard, Mouse? Do you require SRAM? If you only require a specific function, then you can place solder links directly to the pcb. Otherwise, you may want to put pinstakes and use shunts to link the options.
- Blade #2: What options you will use. 1 or 2 SRAMs, FLASH, MicroSD?
- Blade #3: What options you will use. External connections - Spin Studio or General?
- Do you want Blade #2 to load code into Blade #1 and #3 on power-up?
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