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Programming cable for propellor — Parallax Forums

Programming cable for propellor

TransistorToasterTransistorToaster Posts: 149
edited 2006-12-07 06:43 in Propeller 1
Hello,
I'd like to as a few total newbie questions. I am trying to figure out what I need to buy to get started with the Propellor and use it for video output.
1. Do I need to buy a propellor plug if I have a USB2SER?
2. Is the most minimalist standalone system for the Propellor simply a 24lc256 , 5V and 3.3V regulator? (I could program the Propellor through USB2SER and a header, so I would not include them on the board that has the Propellor)
3. Where do I find sample code, or an application note, for NTSC video?
Frank

Post Edited (transistortoaster) : 12/7/2006 6:08:48 AM GMT

Comments

  • Bill HenningBill Henning Posts: 6,445
    edited 2006-12-07 06:01
    most minimal setup is a propeller, and the three transistor circuit hiding on the forums somewhere... but then you need to download the program from the PC whenever the propeller is started up, so its wise to get the eeprom [noparse]:)[/noparse]

    I just wired up a propeller, 3 transistor RS232 interface, three eeprom sockets, and brought the 28 other I/O pins to headers [noparse]:)[/noparse] and I am currently jumpering P24/P25/P26 to the resistor network for TV output for debugging, and P27 to an LED.

    Please note that you need to decouple DTR with a capacitor and invert it so you can connect it to the reset pin on the propeller.

    A 10uF electrolytic capacitor is advised between Vout and GND on the 3.3V regulator, and 0.1uF ceramic caps between power and ground on both sides of the propeller can't hurt.
  • Mike GreenMike Green Posts: 23,101
    edited 2006-12-07 06:09
    1) You do not need a special programmer. You can use a MAX232 or a 3-transistor level translator to convert the RS232 signals to 3.3V logic levels. The PropStick schematic shows the transistor translator circuit. One consideration is that the DTR signal is used for resetting the processor for downloading. If you plan to use the same port for debugging, you may need to put a switch in the reset line. Often when you open a serial port from a program like a terminal emulator, DTR gets asserted which will reset the processor.

    2) Use the PropStick as a working example of the minimalist system. It has the 5V and 3.3V regulators, 24LC256 EEPROM and serial level converter/reset circuit. Unless you are very constrained on cost, I'd strongly suggest using a 24LC512 EEPROM rather than a 24LC256. The extra storage can be used for data and there will likely be some tools to use it for programs as well.

    3) For NTSC video, you only need 3 resistors (270, 560, and 1.1K ohms) and an RCA jack. The Propeller Demo Board schematic shows the connections. You can use any 4-pin group (pins 0-3, 4-7,8-11,12-15, etc.) for this function. If you want to use broadcast mode with simple audio, you'll need another 560 ohm resistor on the 4th pin of the group.
    Mike
  • TransistorToasterTransistorToaster Posts: 149
    edited 2006-12-07 06:11
    Wow, thanks for the fast response. The Propellor does NOT have any EEPROM inside for programs?

    Post Edited (transistortoaster) : 12/7/2006 6:15:44 AM GMT
  • Mike GreenMike Green Posts: 23,101
    edited 2006-12-07 06:16
    1) You can use the USB2SER, but the pinout is different from the Propeller Plug. Functionally they are identical otherwise.

    2) The Propeller has no EEPROM inside. The Propeller Tool downloads to the Propeller's RAM and optionally causes the Propeller to write the whole contents of RAM to the first 32K of EEPROM (and verifies both the RAM download and the copy to EEPROM). The Propeller can run just fine without EEPROM until the power goes off. If you have a battery backup circuit, the Propeller can switch to a very low power mode by stopping all but one cog and by switching the clock to an internal 32kHz RC timer. I don't recall what the minimum supply current is, but it is suitable for use as a data logger running off batteries.

    3) The Propeller Tool has a library that's included with the distribution (and installed by the installer) that includes both a text-only and a text/graphics package that produces standard video (along with several different demo programs).

    Post Edited (Mike Green) : 12/7/2006 6:21:26 AM GMT
  • Harrison.Harrison. Posts: 484
    edited 2006-12-07 06:17
    You can get the 3 transistor level translator schematic here: http://www.parallax.com/propeller/media.asp .

    Also make sure you use an external crystal (5mhz is recommended) for generating video. The internal 12mhz rc oscillator is not fast enough to generate video.
  • TransistorToasterTransistorToaster Posts: 149
    edited 2006-12-07 06:25
    For color video, do I need any external 3.57MHz crystals? For the 80MHz top running speed, an external low frequency crystal with the propellor's internal PLL is enough?
  • Harrison.Harrison. Posts: 484
    edited 2006-12-07 06:40
    You only need an external 5mhz crystal with the internal pll set to pll16. All the colorburst stuff is handled in software and with the onboard hardware video generator.
  • Paul BakerPaul Baker Posts: 6,351
    edited 2006-12-07 06:43
    transistortoaster said...
    Wow, thanks for the fast response. The Propellor does NOT have any EEPROM inside for programs?
    That is correct, there is no on-board EEPROM.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Paul Baker
    Propeller Applications Engineer

    Parallax, Inc.
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