Datasheet

Register Descriptions
56F8357 Technical Data, Rev. 15
Freescale Semiconductor 115
Preliminary
6.5.7.7 CLockout Select (CLKOSEL)—Bits 4–0
Selects clock to be muxed out on the CLKO pin.
• 00000 = SYS_CLK (from OCCS - DEFAULT)
• 00001 = Reserved for factory test—56800E clock
• 00010 = Reserved for factory test—XRAM clock
• 00011 = Reserved for factory test—PFLASH odd clock
• 00100 = Reserved for factory test—PFLASH even clock
• 00101 = Reserved for factory test—BFLASH clock
• 00110 = Reserved for factory test—DFLASH clock
• 00111 = Oscillator output
• 01000 = F
out
(from OCCS)
• 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
6.5.8 GPIO Peripheral Select Register (SIM_GPS)
The GPIO 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 56F8157
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 and Table 6-2. When GPIOC[3:0] are programmed to operate as peripheral I/O, then the
choice between decoder/timer and SPI inputs/outputs is made in the SIM_GPS register 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.