ST92185B datasheet(60/178 Pages) STMICROELECTRONICS

60 / 178 page

60/178

ST92185B - RESET AND CLOCK CONTROL UNIT (RCCU)

4.4 CLOCK CONTROL REGISTERS

MODE REGISTER (MODER)

R235 - Read/Write

Reset Value: 1110 0000 (E0h)

Bit 7:6 = Bits described in Device Architecture

chapter.

Bit 5 = DIV2:

OSCIN Divided by 2.

This bit controls the divide by 2 circuit which oper-

ates on the OSCIN Clock.

0: No division of OSCIN Clock

1: OSCIN clock is internally divided by 2

Bit 4:2 = PRS[2:0]:

Clock Prescaling.

These bits define the prescaler value used to

prescale CPUCLK from INTCLK. When they are

reset, the CPUCLK is not prescaled, and is equal

to INTCLK; in all other cases, the internal clock is

prescaled by the value of these three bits plus one.

Bit 1:0 = Bits described in Device Architecture

chapter.

WAIT CONTROL REGISTER (WCR)

R252 - Read/Write

Reset Value: 0111 1111 (7Fh)

Bit 7 = Reserved, read as “0”.

Bit 6 = WDGEN: refer to Timer/Watchdog chapter.

WARNING. Resetting this bit to zero has the effect

of setting the Timer/Watchdog to the Watchdog

mode. Unless this is desired, this must be set to

“1”.

Bit 5:3 = WDM[2:0]:

Data Memory Wait Cycles.

These bits contain the number of INTCLK cycles

to be added automatically to external Data memo-

ry accesses. WDM = 0 gives no additional wait cy-

cles. WDM = 7 provides the maximum 7 INTCLK

cycles (reset condition).

Bit 2:0 = WPM[2:0]:

Program Memory Wait Cy-

cles.

These bits contain the number of INTCLK cycles

to be added automatically to external Program

memory accesses. WPM = 0 gives no additional

wait cycles, WPM = 7 provides the maximum 7

INTCLK cycles (reset condition).

Note: The number of clock cycles added refers to

INTCLK and NOT to CPUCLK.

WARNING. The reset value of the Wait Control

cles for external memory. To get optimum per-

formance from the ST9 when used in single-chip

mode (no external memory) the user should write

the WDM2,1,0 and WPM2,1,0 bits to “0”.

DIV2

PRS2

PRS1

PRS0

WDGEN WDM2 WDM1

WDM0

WPM2 WPM1 WPM0

ST92185B 数据表(PDF) 60 Page - STMicroelectronics

ST92185B 数据表(HTML) 60 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

数据表下载