Motorola MPC823e Reference Manual page 532

Communication Processor Module
GM1—Gate Mode for Pin 1
This bit is only valid if the gate function is enabled in timer 1 or 2.
0 = Restart gate mode. A falling TGATE1 pin enables and restarts the count and a
rising edge of TGATE1 disables the count.
1 = Normal gate mode. This mode is the same as 0, except the falling edge of the
TGATE1 pin does not restart the count value in the timer counter.
16.4.2.3 TIMER MODE REGISTERS. The 16-bit, memory-mapped, read/write timer mode
registers (TMR1–TMR4) are identical and cleared by reset. To avoid erratic behavior, the
TGCR must be initialized before the TMRx register. The only exception is that the RST bit
in the TGCR can be modified at any time.
TMR1–TMR4
BIT 0 1 2
FIELD
RESET
R/W
ADDR (IMMR & 0xFFFF0000) + 0x990 (TMR1), 0x992 (TMR2), 0x9A0 (TMR3), 0x9A2 (TMR4)
PS—Prescaler Value
The prescaler is programmed to divide the clock input by a value between 1 and 256. A
00000000 value divides the clock by 1 and 11111111 divides it by 256.
CE—Capture Edge and Enable Interrupt
00 = Disable interrupt on capture event; capture function is disabled.
01 = Capture on rising TINx edge only and enable interrupt on capture event.
10 = Capture on falling TINx edge only and enable interrupt on capture event.
11 = Capture on any TINx edge and enable interrupt on capture event.
OM—Output Mode (Only Valid for TMR1 and TMR2)
0 = Active-low pulse on TOUT1 or TOUT2 for one timer input clock cycle as defined by
the ICLK bits. Thus, TOUTx may be low for one general system clock period, one
general system clock/16 period, or one TINx pin clock cycle period. Changes to
TOUTx occur on the falling edge of the system clock.
1 = Toggle the TOUTx pin. Changes to TOUTx occur on the falling edge of the system
clock.
ORI—Output Reference Interrupt Enable
0 = Disable interrupt for reference that is reached. This does not affect an interrupt on
the capture function.
1 = Enable interrupt when the reference value is reached.
16-78
3 4 5 6 7
PS
0
R/W
MPC823e REFERENCE MANUAL
8 9 10 11 12
CE OM ORI FRR
0 0 0 0
R/W R/W R/W R/W
13 14 15
ICLK GE
0 0
R/W R/W
MOTOROLA