Is there a hookup for a bare chip somewhere...?
Steve Hobley
Posts: 4
On a complete whim I just bought a bare 40 pin DIP propeller chip.
I don't have the kit, just the chip.
But I do have an FTDI serial<->usb cable and fearless determination.
Is there a bare hookup diagram somewhere to get this chip a spinnin' ?
Steve
I don't have the kit, just the chip.
But I do have an FTDI serial<->usb cable and fearless determination.
Is there a bare hookup diagram somewhere to get this chip a spinnin' ?
Steve
Comments
Page 5 of the Data sheet.
-Ron
If your FTDI serial/usb chip is 5V make sure and use 2K ohm resistors on the Prop rx (P31).
Make sure you connect both sets of power and ground on the prop. There are 4 power/gnd pins and the BOE must be connected to gnd too. You do not require anything else (no xtal, etc). Put a 0.1uF capacitor across the power/ground pairs on both sides.
Now you can connect up the FTDI chip as per the circuit diagram - Get the Propeller Demo BOard (non USB) circuit diagram from the Parallax store section.
Sing out if you have problems.
I can't find a non-usb schematic, just one that shows the USB hookup via a FT232RQ
http://www.parallax.com/dl/docs/prod/prop/PropDemoDschem.pdf.
Should I just discount the FT232 section of this schematic?
Also - just to confirm, following this schematic I:
* Don't need an external 5Mhz crystal
* All power should be 3.3v
* Do I need to condition the output of the FTDI cable in some way - as TTL is almost certainly 5v.
?
Steve
P.S. I sometimes fake 3.3v using a couple of diodes, and rely on the voltage drop to get the supply down to 3.5v - is this not recommended for the Propeller?
http://www.parallax.com/dl/docs/prod/prop/PropStick-v1.2.pdf
Duane
The serial schematic is below the USB schematic. Just 2 transistors and a few resistors.
Steve
* You don't need a 5Mhz xtal, it will default to internal RC clock
* The Prop needs a voltage on each of its 2-4 Vdd pins, 3.0v~3.6v is good. The diode drop method isn't ideal but may work to get you started if combined with a cap (10uF??) to restrain the initial spike as the diodes begin to conduct.
(* The FT232 puts out 3v3 TTL logic, no series resistors required <- INCORRECT see andys note below)
See this thread... I like Jazzed's ultra minimalist approach supergluing the header onto the DIP40
http://forums.parallax.com/showthread.php?114944-Ultra-Minimum-Propeller-Fact-or-Fiction&highlight=jazzed+logic+analyzer
good luck
tubular
http://www.parallax.com/Portals/0/Downloads/docs/prod/prop/32212-32812-PropellerProtoBoard-v1.3.pdf
The diagram on the last page gives the FTDI schematic....
You do not require the leds and their resistors
Any npn transistor will do. I used a P2N2222. Just be careful of the pinout.
You can join 3V3out to VccIO with a 0.1uF cap to ground instead of using the power from the prop. This output is capable of supplying 50mA at 3V3 so you can use this to power the prop provided you do not connect many circuits to the prop. If you use a led, use a superbright and 10K or else use a 3K3 to keep the current down.
The pin numbers for the FTDI chip are the QFN package
I will post a minimal circuit diagram shortly.
This cables sometimes have no DTR pin brought out, then you can use the RTS pin and change the settings in the PropellerTool for that. In both cases the R-C-Transistor circuit to generate a reset puls is nessecary (see the DemoBoard schematic in the datasheet).
Andy
Edit: Make sure you connect also the BOE pin of the Prop to ground, this enables an internal PullUp on the Reset pin.
If your cable has RTS instead of DTR out, just use this instead and adjust your terminal program to use RTS insead of DTR.