Humm I'm using i2c in my project and have a '877 talking to two phillips
i/o expander chips..what size
cap is supposed to go on SDA?


At 07:26 AM 4/27/2001 -0400, you wrote:
>> I need a bunch (max 6) 16f877 pic's to be able to talk to each other.
>From
>> the literature on the Microchip site I gather I can use SSP with
>SPI(Master
>> Mode) and I2C(Master/Slave).  Is this the only(best) way to have my pic's
>> talk?
>
>Of course not.  You can invent an infinite number of schemes.
>
>> What are the benefits of SPI to I2C?
>
>SPI can go faster because each line is actively driven in both directions,
>and two bits (one in each direction) are transferred each clock cycle.  On
>the other hand, it requires three bus wires instead of two, and usually a
>separate "chip select" line per slave device.
>
>IIC specifies a bit more protocol than just pumping bits between master and
>slave.  It is therefore more flexible, and the PIC implementation allows for
>flow control in one direction at least.
>
>I would use IIC unless you are trying to go off board or the transfer rate
>isn't fast enough.  Due to a bug in the PIC implementation, you need to put
>a capacitor on the SDA, and I personally won't use it above 500Kbits/second.
>
>
>********************************************************************
>Olin Lathrop, embedded systems consultant in Littleton Massachusetts
>(978) 742-9014, olin@embedinc.com, http://www.embedinc.com
>
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>
>
>

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