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USB Documentaion — Parallax Forums

USB Documentaion

cfoxcfox Posts: 16
edited 2011-12-30 23:58 in Propeller 1
Hi everyone. I'm building a reprap, and as part of that I've decided to make my own electronics based on our friend the Propeller. The QuickStart board, in fact.

With this in mind, I'd like to use the USB interface as a live connection to an app (that I have yet to write) on the PC end of things.

So, I'm looking for USB communication documentation, or serial, or whatever I would need to make this happen. I've cruised the website and the forums, but a forum search on USB turns up zero results.

Can anyone point me to some docs so I can get this party started?

Thanks,
Colin

Comments

  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2011-12-30 22:23
    The onboard FTDI chip does all the heavy lifting for you. From there to the Propeller, it's just an asynchronous serial protocol: receive on P31, transmit on P30, your choice of baudrates.

    -Phil
  • Jorge PJorge P Posts: 385
    edited 2011-12-30 23:30
    @Colin
    The QuickStart schematics show that it uses the FTDI232RL IC, http://www.ftdichip.com/Products/ICs/FT232R.htm the datasheet and appnotes might be helpful to you, but I would not go around messing with that chips settings since it might render the QuickStart unusable, unless Parallax posts how they configure the chip by default.
    FT232R-DataSheet-Section-4.2 wrote:
    Internal EEPROM. The internal EEPROM in the FT232R is used to store USB Vendor ID (VID), Product ID (PID), device serial number, product description string and various other USB configuration descriptors. The internal EEPROM is also used to configure the CBUS pin functions. The FT232R is supplied with the internal EEPROM pre-programmed as described in Section 8. A user area of the internal EEPROM is available to system designers to allow storing additional data. The internal EEPROM descriptors can be programmed in circuit, over USB without any additional voltage requirement. It can be programmed using the FTDI utility software called MPROG, which can be downloaded from FTDI Utilities on the FTDI website (www.ftdichip.com).

    So unless you have Parallax's data, it, the QuickStart board, may become un-programmable if you send it your own program. If you are able to program the FTDI chip, the schematics show that there are two free SBUS pins unused for the QuickStart Schematic. Parallax might also just keep the FTDI chips default factory values. I haven't seen much posted on the forum about this, But since Parallax uses the CBUS for the LED's they most likely have it programmed a certain way!
  • Cluso99Cluso99 Posts: 18,069
    edited 2011-12-30 23:58
    JorgeP: There is no special programming of the FT232RL chip. I use them all the time and do nothing with them. That is their beauty but it comes at a $.

    cfox: Welcome to the fabulous world of the prop. The RepRap is ideally suited to the prop chip. However, we still have a way to go to get code running.
    The USB link is simple - you just use the FullDuplexObject which outputs serial and we usually run at 115200 baud. The pc end looks like any com port.

    Phil has a MakerBot thread in the builders forum (see the forum links at the top of the page).

    I have two pcbs that may help. One is a 1.8"sq t/hole design passive motherboard that accepts 4 pololu stepper driver boards (use the A4988 version as it has better protection). I have a pcb using the A4982 or A4984 but I have not assembled it yet. The motherboard has a 1x14 pin header to connect to a prop board. (see my web link in my signature). Basically it is the Sanguino stepper section. I have not yet finalised the Mosfet driver pcb (for hotend and heated bed). I plug these into a prop board of mine, but almost any prop board will work.
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