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53
T48C862-R8
4590B–4BMCU–02/03
Timer 2 Compare and
Compare Mode Registers
Timer 2 has two separate compare registers, T2CO1 for the 4-bit stage and T2CO2 for
the 8-bit stage of Timer 2. The timer compares the contents of the compare register cur-
rent counter value and if it matches it generates an output signal. Dependent on the
timer mode, this signal is used to generate a timer interrupt, to toggle the output flip-flop
as SSI clock or as a clock for the next counter stage.
In the 12-bit timer mode, T2CO1 contains bits 0 to 3 and T2CO2 bits 4 to 11 of the 12-bit
compare value. In all other modes, the two compare registers work independently as a
4- and 8-bit compare register.
When assigned to the compare register a compare event will be suppressed.
Timer 2 Compare Mode
Register (T2CM)
Address: "7"hex - Subaddress: "3"hex
Timer 2 COmpare Register 1
(T2CO1)
Address: "7"hex - Subaddress: "4"hex
In prescaler mode the clock is bypassed if the compare register T2CO1 contains 0.
Bit 3Bit 2Bit 1Bit 0
T2OTM T2CTM T2RM T2IM Reset value: 0000b
T2OTM Timer 2 Overflow Toggle Mask bit
T2OTM = 0, disable overflow toggle
T2OTM = 1, enable overflow toggle, a counter overflow (OVF2) toggles output
flip-flop (TOG2). If the T2OTM-bit is set, only a counter overflow can
generate an interrupt except on the Timer 2 output mode 7.
T2CTM Timer 2 Compare Toggle Mask bit
T2CTM = 0, disable compare toggle
T2CTM = 1, enable compare toggle, a match of the counter with the compare
register toggles output flip-flop (TOG2). In Timer 2 output mode 7 and
when the T2CTM-bit is set, only a match of the counter with the
compare register can generate an interrupt.
T2RM Timer 2 Reset Mask bit
T2RM = 0, disable counter reset
T2RM = 1, enable counter reset, a match of the counter with the compare register
resets the counter
T2IM Timer 2 Interrupt Mask bit
T2IM = 0, disable Timer 2 interrupt
T2IM = 1, enable Timer 2 interrupt
Timer 2 Output Mode T2OTM T2CTM Timer 2 Interrupt Source
1, 2, 3, 4, 5 and 6 0 x Compare match (CM2)
1, 2, 3, 4, 5 and 6 1 x Overflow (OVF2)
7 x 1 Compare match (CM2)
Write cycle Bit 3 Bit 2 Bit 1 Bit 0 Reset value: 1111b