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communicating an SX with the prop — Parallax Forums

communicating an SX with the prop

edlikestoboogieedlikestoboogie Posts: 71
edited 2007-07-22 15:29 in Propeller 1
I've been having trouble trying to communicate the prop as the master, and the SX as a slave... Bare with me since this the first time I've ever tried serial communication, and its been tough, to say the least.. and i don't own an oscilloscope.. I tried looking up code in SX/b for I2C slave code, which there really isn't.. Has anyone else had success communicating between these two chips? I need the SX to help out because the prop doesn't have enough I/O pins.. Any advice or a few good points of direction would be really great.

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2007-07-22 04:13
    There are other ways to add I/O pins, like the I2C I/O port expanders: MCP23008 and PCA9554 (8 bit) and the MCP23017 (16 bit). You can also use the 74HC595 (8 bit output) and the 74HC165 (8 bit input). If you want to use an SX, the easiest way to communicate between them is to use asynchronous serial at 9600 Baud or 19.2KBaud. The FullDuplexSerial driver included with the Propeller Tool can easily handle this.
  • Marc GebauerMarc Gebauer Posts: 60
    edited 2007-07-22 04:25
    Making a device comunicate as an i2c slave without the proper licensing probably would cause some copywrite infringement. So you won't see much published on the subject. But there is some code that has been written for the prop. http://forums.parallax.com/showthread.php?p=617209

    If you need more IO, I would suggest using a port expander. I've used·the PCF8574, which uses i2c protocol·and·has 8 ports. 8·of these devices can be addressed on the same bus.·You should also check out the PCA9554. Either can be placed on the same i2c bus as the propeller's program EEPROM.·I think there is a 16 port version.·

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  • Paul BakerPaul Baker Posts: 6,351
    edited 2007-07-22 07:21
    The last I heard, Philipps is no longer enforcing it's patent on I2C slave devices.

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    Paul Baker
    Propeller Applications Engineer

    Parallax, Inc.
  • LeonLeon Posts: 7,620
    edited 2007-07-22 10:15
    SPI would be easier, and it 's a lot faster. Doing it in software only uses two pins.

    Leon

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    Amateur radio callsign: G1HSM
    Suzuki SV1000S motorcycle
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2007-07-22 15:29
    Marc Gebauer,

    Phillips released their I2C license on October 1st, 2006

    www.nxp.com/products/interface_control/i2c/licensing/

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
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