MC56F836 Freescale Semiconductor, Inc, MC56F836 Datasheet - Page 120

• Manufacturer Part Number: MC56F836
• Description: 56f8300 16-bit Digital Signal Controllers
• Manufacturer: Freescale Semiconductor, Inc

6.5.8
Some GPIO pads can have more than one peripheral selected as the alternate function instead of GPIO.
For these pads, this register selects which of the alternate peripherals are actually selected for the GPIO
peripheral function. This applies to GPIOC, pins 0-3, and to GPIOD, pins 0 and 1.
The GPIOC Peripheral Select Register can be used to multiplex out any one of the three alternate
peripherals for GPIOC. The default peripheral is Quad Decoder 1 and Quad Timer B (NOT available in
the 56F8165 device); these peripherals work together.
The four I/O pins associated with GPIOC can function as GPIO, Quad Decoder 1/Quad Timer B, or as
SPI 1 signals. GPIO is not the default and is enabled/disabled via the GPIOC_PER, as shown in
Figure 6-10
choice between decoder/timer and SPI inputs/outputs is made in the SIM_GPS and in conjunction with the
Quad Timer Status and Control Registers (SCR). The default state is for the peripheral function of
GPIOC[3:0] to be programmed as decoder functions. This can be changed by altering the appropriate
controls in the indicated registers.
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00110 = Reserved for factory test—DFLASH clock
00111 = Oscillator output
01000 = F
01001 = Reserved for factory test—IPB clock
01010 = Reserved for factory test—Feedback (from OCCS, this is path to PLL)
01011 = Reserved for factory test—Prescaler clock (from OCCS)
01100 = Reserved for factory test—Postscaler clock (from OCCS)
01101 = Reserved for factory test—SYS_CLK2 (from OCCS)
01110 = Reserved for factory test—SYS_CLK_DIV2
01111 = Reserved for factory test—SYS_CLK_D
10000 = ADCA clock
10001 = ADCB clock
GPIO Peripheral Select Register (SIM_GPS)
and
out
Table
(from OCCS)
6-2. When GPIOC[3:0] are programmed to operate as peripheral I/O, then the
56F8365 Technical Data, Rev. 7
Freescale Semiconductor
Preliminary