
PSB 2115
PSF 2115
Detailed Register Description
Semiconductor Group
244
11.97
4.3.8
Value after reset: (not defined, previous value)
TIMR1 - Timer 1 Register (Read/Write)
CNT
... The meaning depends on the selected timer mode (MODED:TMD):
Internal Timer Mode (TMD=1)
CNT indicates the maximum number of S commands “N1” which are transmitted
autonomously by the IPAC after expiration of time period T1 (retry, according to HDLC).
The internal procedure will be
started
in automode:
after start of an I-frame transmission or
after an ’RNR’ S-frame has been received
After the last retry a timer interrupt (TIN-bit in ISTAD) is generated.
The timer procedure will be
stopped
when
a TIN interrupt is generated. The time between the start of an I-frame transmission or
reception of an ’RNR’ S-frame and the generation of a TIN interrupt is equal to:
(
CNT + 1 ) x T1
or the TIMR1 is written
or a positive or negative acknowledgment has been received.
Note: The maximum value of CNT can be 6. If CNT is set to 7, the number of retries is
unlimited.
External Timer Mode (TMD=0)
CNT together with VALUE determine the time period T2 after which a TIN interrupt will
be generated in the normal case:
T2 = CNT x 2.048 sec + T1
with
T1 = ( VALUE+1 ) x 0.064 sec
When TLP=1 (test loop activated, SPCR register):
T2 = 16348 x CNT x DCL + T1
with
T1 = 512 x ( VALUE+1 ) x DCL
DCL denotes the period of the DCL clock.
The timer can be started by setting the STI-bit in CMDRD and will be stopped when a
TIN interrupt is generated or the TIMR1 register is written.
Note: If CNT is set to 7, a TIN interrupt is indefinitely generated after every expiration of
T1.
VALUE
... Determines the time period T1
T1 = ( VALUE + 1 ) x 0.064 sec (SPCR:TLP = 0, normal mode)
T1 = 512 x ( VALUE + 1 ) x DCL (SPCR:TLP = 1, test mode)
7
5
4
0
TIMR1
CNT
VALUE
(A3)