PXN20RM Datasheet, PDF (1166/1376 Pages) Freescale Semiconductor, Inc – PXN20 Microcontroller

Nexus Development Interface (NDI)
36.5.4.4 Port Configuration Register (PCR)
The PCR is used to select the NPC mode of operation, enable MCKO and select the MCKO frequency,
and enable or disable MCKO gating. This register should be configured as soon as the NDI is enabled.
The PCR register may be rewritten by the debug tool subsequent to the enabling of the NPC for low power
debug support. In this case, the debug tool may set and clear the LP_DBG_EN and SLEEP_SYNC bits,
but must preserve the original state of the remaining bits in the register.
NOTE
The mode (MCKO_GT) or clock division (MCKO_DIV) bits must not be
modified after MCKO has been enabled. Changing the mode or clock
division while MCKO is enabled can produce unpredictable results.
Reg Index: 0x7F
Access: User read/write
31
30
29
28 27 26
25
24 23 22 21 20 19 18 17
16
R
W
FPM
MCKO MCKO
_GT _EN
MCKO_DIV
EVT ^{0 0 0 0 0 0 0 0}
_EN
0
Reset 0
0
0
000
0
00000000
0
15
14
R _{LP_DBG} 0
W ^_EN
Reset 0
0
13
12 11 10
9
8
7
6
5
4
3
2
1
0
0
0 0 0 _SLEEP 0 0 0 0 0 0 0 0 _PSTAT
_SYNC
_EN
0
000
0
00000000
0
Figure 36-7. Port Configuration Register (PCR)
Table 36-9. PCR Field Descriptions
Field
FPM
MCKO_GT
MCKO_EN
Description
Full Port Mode.The value of the FPM bit determines if the auxiliary output port uses the full MDO port or a
reduced MDO port to transmit messages.
0 A subset of MDO pins are used to transmit messages.
Note: All MDO pins are used to transmit messages.This bit must always be set when configuring the NDI.
MCKO Clock Gating Control.This bit is used to enable or disable MCKO clock gating. If clock gating is
enabled, the MCKO clock is gated when the NPC is in enabled mode but not actively transmitting messages
on the auxiliary output port. When clock gating is disabled, MCKO is allowed to run even if no auxiliary output
port messages are being transmitted.
0 MCKO gating is disabled.
1 MCKO gating is enabled.
MCKO Enable. This bit enables the MCKO clock to run. When enabled, the frequency of MCKO is
determined by the MCKO_DIV field.
0 MCKO clock is driven to zero.
1 MCKO clock is enabled.
36-16
PXN20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor