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MC9S08DZ128 Module pin sharing? Specifically can SPI be linked to 2 sets of pins.

Question asked by Scott Miller on Feb 17, 2015

I have a design where I am using the SPI pins on MC9S08DZ128 (48 pin pkg) PTE4/SCL1/MOSI1 and PTE5/SDA1/MISO1 to interface to a peripheral device.  I would also like to use another peripheral device on a new iteration of this design, but unfortunately I can't access PT4 and PTE5 for this new device (long story).  I have wired the new device up to PTF2/TPM1CLK/SCL1 and PTF3/TPM2CLK/SDA1 thinking I could map these pins to PTE4 and 5, and control both devices using SPI (of course I have a separate chip select i/o to select the right device).  However, using processor expert (in CW 6.3), I am not understanding how to accomplish this.  Can you please assist me?  The datasheet overall block diagram shows the linkage between pins.


When I did the hardware design for this several months ago, my thought process was: 1) If pin sharing/linking works, great! If not --> 2) Use I2C to emulate SPI (with a few caveats).. if this doesn't work --> 3) use the timers on those pins.... OR 4) bit bang SPI using pins as I/O .  But I'm really hoping the pins can be linked and so I can use the SPI module.

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