ST92T163 ST Microelectronics, ST92T163 Datasheet - Page 109

• Manufacturer Part Number: ST92T163
• Description: 8/16-BIT FULL SPEED USB MCU FOR COMPOSITE DEVICES WITH 16 ENDPOINTS
• Manufacturer: ST Microelectronics

TIMER/WATCHDOG (Cont’d)
8.1.5 Register Description
The Timer/Watchdog is associated with 4 registers
mapped into Group F, Page 0 of the Register File.
WDTHR: Timer/Watchdog High Register
WDTLR: Timer/Watchdog Low Register
WDTPR: Timer/Watchdog Prescaler Register
WDTCR: Timer/Watchdog Control Register
Three additional control bits are mapped in the fol-
lowing registers on Page 0:
Watchdog Mode Enable, (WCR.6)
Top Level Interrupt Selection, (EIVR.2)
Interrupt A0 Channel Selection, (EIVR.1)
Note: The registers containing these bits also con-
tain other functions. Only the bits relevant to the
operation of the Timer/Watchdog are shown here.
Counter Register
This 16 bit register (WDTLR, WDTHR) is used to
load the 16 bit counter value. The registers can be
read or written “on the fly”.
TIMER/WATCHDOG HIGH REGISTER (WDTHR)
R248 - Read/Write
Register Page: 0
Reset value: 1111 1111 (FFh)
Bit 7:0 = R[15:8] Counter Most Significant Bits .
TIMER/WATCHDOG LOW REGISTER (WDTLR)
R249 - Read/Write
Register Page: 0
Reset value: 1111 1111b (FFh)
Bit 7:0 = R[7:0] Counter Least Significant Bits.
R15
R7
7
7
R14
R6
R13
R5
R12
R4
R11
R3
R10
R2
R9
R1
R8
R0
0
0
TIMER/WATCHDOG PRESCALER REGISTER
(WDTPR)
R250 - Read/Write
Register Page: 0
Reset value: 1111 1111 (FFh)
Bit 7:0 = PR[7:0] Prescaler value.
A programmable value from 1 (00h) to 256 (FFh).
Warning : In order to prevent incorrect operation of
the Timer/Watchdog, the prescaler (WDTPR) and
counter (WDTRL, WDTRH) registers must be ini-
tialised before starting the Timer/Watchdog. If this
is not done, counting will start with the reset (un-in-
itialised) values.
WATCHDOG TIMER CONTROL REGISTER
(WDTCR)
R251- Read/Write
Register Page: 0
Reset value: 0001 0010 (12h)
Bit 7 = ST_SP: Start/Stop Bit .
This bit is set and cleared by software.
0: Stop counting
1: Start counting (see Warning above)
Bit 6 = S_C: Single/Continuous .
This bit is set and cleared by software.
0: Continuous Mode
1: Single Mode
Bit 5:4 = INMD[1:2]: Input mode selection bits .
These bits select the input mode:
ST_SP
PR7
INMD1
7
7
0
0
1
1
ST92163 - TIMER/WATCHDOG (WDT)
S_C
PR6
INMD2
INMD1
PR5
0
1
0
1
INMD2
PR4
Gated Input (Reset value)
INEN
PR3
Retriggerable Input
Triggerable Input
INPUT MODE
Event Counter
OUTMD
PR2
WROUT
PR1
109/224
OUTEN
PR0
0
0