
Chapter 2 Port Integration Module (S12XHZPIMV1)
MC9S12XHZ512 Data Sheet, Rev. 1.06
Freescale Semiconductor
79
2.3.5.3
ECLK Control Register (ECLKCR)
Read: Anytime. Write: Anytime.
The ECLKCTL register is used to control the availability of the free-running clocks and the free-running
clock divider.
Module Base + 0x0055
76543210
R
NECLK
NCLKX2
0000
EDIV1
EDIV0
W
Reset
01
1 NECLK reset value is 1 in emulation single-chip and normal single-chip modes.
1000000
= Reserved or Unimplemented
Figure 2-16. ECLK Control Register (ECLKCR)
Table 2-11. ECLKCTL Field Descriptions
Field
Description
7
NECLK
No ECLK — This bit controls the availability of a free-running clock on the ECLK pin. Clock output is always
active in emulation modes and if enabled in all other operating modes.
0 ECLK enabled
1 ECLK disabled
6
NCLKX2
No ECLKX2 — This bit controls the availability of a free-running clock on the ECLKX2 pin. This clock has a xed
rate of twice the internal bus clock. Clock output is always active in emulation modes and if enabled in all other
operating modes.
0 ECLKX2 is enabled
1 ECLKX2 is disabled
1–0
EDIV[1:0]
Free-Running ECLK Divider — These bits determine the rate of the free-running clock on the ECLK pin
r. The
usage of the bits is shown in
Table 2-12. Divider is always disabled in emulation modes and active as
programmed in all other operating modes.
Table 2-12. Free-Running ECLK Clock Rate
EDIV[1:0]
Rate of Free-Running ECLK
00
ECLK = Bus clock rate
01
ECLK = Bus clock rate divided by 2
10
ECLK = Bus clock rate divided by 3
11
ECLK = Bus clock rate divided by 4