ST6252C STMicroelectronics, ST6252C Datasheet - Page 41

• Manufacturer Part Number: ST6252C
• Description: 8 Bit ST6 Microcontroller with 4x8-bitADC 1x8-bit TIMER, 1x8-bitAR TIMER
• Manufacturer: STMicroelectronics

Specifications of ST6252C

• Data Ram: 128 bytes
• Data Eeprom: 64 bytes (none on ST62T52C)

TIMER (Cont’d)
A write to the TCR register will predominate over
the 8-bit counter decrement to 00h function, i.e. if a
write and a TCR register decrement to 00h occur
simultaneously, the write will take precedence,
and the TMZ bit is not set until the 8-bit counter
reaches 00h again. The values of the TCR and the
PSC registers can be read accurately at any time.
4.2.4 Timer Registers
Timer Status Control Register (TSCR)
Address: 0D4h — Read/Write
Bit 7 = TMZ: Timer Zero bit
A low-to-high transition indicates that the timer
count register has decrement to zero. This bit
must be cleared by user software before starting a
new count.
Bit 6 = ETI: Enable Timer Interrup
When set, enables the timer interrupt request
(vector #4). If ETI=0 the timer interrupt is disabled.
If ETI=1 and TMZ=1 an interrupt request is gener-
ated.
Bit 5 = D5: Reserved
Must be set to “1”.
Bit 4 = D4
Do not care.
Bit 3 = PSI: Prescaler Initialize Bit
Used to initialize the prescaler and inhibit its count-
ing. When PSI=“0” the prescaler is set to 7Fh and
the counter is inhibited. When PSI=“1” the prescal-
er is enabled to count downwards. As long as
TMZ
7
ETI
D5
D4
PSI
PS2
PS1
PS0
0
PSI=“0” both counter and prescaler are not run-
ning.
Bit 2, 1, 0 = PS2, PS1, PS0: Prescaler Mux. Se-
lect. These bits select the division ratio of the pres-
caler register.
Table 13. Prescaler Division Factors
Timer Counter Register (TCR)
Address: 0D3h — Read/Write
Bit 7-0 = D7-D0: Counter Bits.
Prescaler Register PSC
Address: 0D2h — Read/Write
Bit 7 = D7: Always read as "0".
Bit 6-0 = D6-D0: Prescaler Bits.
D7
D7
7
7
PS2
0
0
0
0
1
1
1
1
D6
D6
D5
D5
ST6252C ST6262B ST6262C
PS1
1
0
0
1
1
0
0
1
D4
D4
D3
D3
PS0
1
0
1
0
1
0
1
0
D2
D2
Divided by
D1
D1
128
16
32
64
8
1
2
4
41/75
D0
D0
0
0