PIC10F200-ESLASHP datasheet(35/96 Pages) MICROCHIP

35 / 96 page

DS41239D-page 33

PIC10F200/202/204/206

7.0

TIMER0 MODULE AND TMR0

The Timer0 module has the following features:

• 8-bit timer/counter register, TMR0

• Readable and writable

• 8-bit software programmable prescaler

• Internal or external clock select:

- Edge select for external clock

- External clock from either the T0CKI pin or

from the output of the comparator

Figure 7-1 is a simplified block diagram of the Timer0

module.

Timer mode is selected by clearing the T0CS bit

(OPTION<5>). In Timer mode, the Timer0 module will

increment every instruction cycle (without prescaler). If

TMR0 register is written, the increment is inhibited for

the following two cycles (Figure 7-2 and Figure 7-3).

The user can work around this by writing an adjusted

value to the TMR0 register.

There are two types of Counter mode. The first Counter

mode uses the T0CKI pin to increment Timer0. It is

selected by setting the T0CS bit (OPTION<5>), setting

the CMPT0CS bit (CMCON0<4>) and setting the

COUTEN bit (CMCON0<6>). In this mode, Timer0 will

increment either on every rising or falling edge of pin

T0CKI. The T0SE bit (OPTION<4>) determines the

source edge. Clearing the T0SE bit selects the rising

edge. Restrictions on the external clock input are

discussed in detail in Section 7.1 “Using Timer0 with

an External Clock (PIC10F204/206)”.

The second Counter mode uses the output of the com-

parator to increment Timer0. It can be entered in two

different ways. The first way is selected by setting the

T0CS bit (OPTION<5>) and clearing the CMPT0CS bit

(CMCON<4>); (COUTEN [CMCON<6>]) does not

affect this mode of operation. This enables an internal

connection between the comparator and the Timer0.

The second way is selected by setting the T0CS bit

(OPTION<5>),

setting

the

CMPT0CS

bit

(CMCON0<4>) and clearing the COUTEN bit

(CMCON0<6>). This allows the output of the compara-

tor onto the T0CKI pin, while keeping the T0CKI input

active. Therefore, any comparator change on the

COUT pin is fed back into the T0CKI input. The T0SE

bit (OPTION<4>) determines the source edge. Clear-

ing the T0SE bit selects the rising edge. Restrictions on

the external clock input as discussed in Section 7.1

“Using Timer0 with an External Clock (PIC10F204/

206)”

The prescaler may be used by either the Timer0

module or the Watchdog Timer, but not both. The

prescaler assignment is controlled in software by the

control bit, PSA (OPTION<3>). Clearing the PSA bit

will assign the prescaler to Timer0. The prescaler is not

readable or writable. When the prescaler is assigned to

the Timer0 module, prescale values of 1:2, 1:4,...,

1:256 are selectable. Section 7.2 “Prescaler” details

the operation of the prescaler.

A summary of registers associated with the Timer0

module is found in Table 7-1.

FIGURE 7-1:

TIMER0 BLOCK DIAGRAM (PIC10F204/206

)

Note 1:

Bits T0CS, T0SE, PSA, PS2, PS1 and PS0 are located in the OPTION register.

The prescaler is shared with the Watchdog Timer (Figure 7-5).

Bit CMPT0CS is located in the CMCON0 register, CMCON0<4>.

T0CS(1)

FOSC/4

Programmable

Prescaler(2)

Sync with

Internal

Clocks

TMR0 Reg

PSOUT

(2 TCY delay)

PSOUT

Data Bus

PSA(1)

PS2, PS1, PS0(1)

Sync

T0SE(1)

T0CKI

CMPT0CS(3)

Internal

Comparator

Output

PIC10F200-E/P датащи(PDF) 35 Page - Microchip Technology

PIC10F200-E/P датащи(HTML) 35 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96

датащи скачать

ссылки URL