PIC16HV540-04/P Microchip Technology, PIC16HV540-04/P Datasheet - Page 28

• Manufacturer Part Number: PIC16HV540-04/P
• Description: IC MCU OTP 512X12 18DIP
• Manufacturer: Microchip Technology
• Series: PIC® 16Cr

Specifications of PIC16HV540-04/P

• Core Size: 8-Bit
• Program Memory Size: 768B (512 x 12)
• Core Processor: PIC
• Speed: 4MHz
• Peripherals: Brown-out Detect/Reset, POR, WDT
• Number Of I /o: 12
• Program Memory Type: OTP
• Ram Size: 25 x 8
• Voltage - Supply (vcc/vdd): 3.5 V ~ 15 V
• Oscillator Type: External
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 18-DIP (0.300", 7.62mm)
• Controller Family/series: PIC16HV
• No. Of I/o's: 12
• Ram Memory Size: 25Byte
• Cpu Speed: 4MHz
• No. Of Timers: 1
• Digital Ic Case Style: DIP
• Processor Series: PIC16H
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 25 B
• Maximum Clock Frequency: 4 MHz
• Number Of Programmable I/os: 12
• Number Of Timers: 8
• Operating Supply Voltage: 3.5 V to 15 V
• Maximum Operating Temperature: + 70 C
• Mounting Style: Through Hole
• Minimum Operating Temperature: 0 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: AC164001 - MODULE SKT PROMATEII 18/28DIP
• Eeprom Size: -
• Data Converters: -
• Connectivity: -
• Lead Free Status / Rohs Status: Details

PIC16HV540
6.2
An 8-bit counter is available as a prescaler for the
Timer0 module, or as a postscaler for the Watchdog
Timer (WDT) (WDT postscaler not implemented on
PIC16C52), respectively (Section 6.1.2). For simplicity,
this counter is being referred to as “prescaler” through-
out this data sheet. Note that the prescaler may be
used by either the Timer0 module or the WDT, but not
both. Thus, a prescaler assignment for the Timer0
module means that there is no prescaler for the WDT,
and vice-versa.
The PSA and PS2:PS0 bits (OPTION<3:0>) determine
prescaler assignment and prescale ratio.
When assigned to the Timer0 module, all instructions
writing
MOVWF 1, BSF 1,x, etc.) will clear the prescaler.
When assigned to WDT, a CLRWDT instruction will clear
the prescaler along with the WDT. The prescaler is nei-
ther readable nor writable. On a RESET, the prescaler
contains all '0's.
6.2.1
The prescaler assignment is fully under software con-
trol (i.e., it can be changed “on the fly” during program
execution). To avoid an unintended device RESET, the
following instruction sequence (Example 6-1) must be
executed when changing the prescaler assignment
from Timer0 to the WDT.
EXAMPLE 6-1:
To change prescaler from the WDT to the Timer0 mod-
ule, use the sequence shown in Example 6-2. This
sequence must be used even if the WDT is disabled. A
CLRWDT instruction should be executed before switch-
ing the prescaler.
DS40197B-page 28
1. CLRWDT
2. CLRF
3. MOVLW
4. OPTION
5. CLRWDT
6. MOVLW
7. OPTION
to
Prescaler
SWITCHING PRESCALER ASSIGNMENT
the
TMR0
'00xx1111’b
'00xx1xxx’b
TMR0
CHANGING PRESCALER
(TIMER0 WDT)
;Clear WDT
;Clear TMR0 & Prescaler
;These 3 lines (5, 6, 7)
; are required only if
; desired
;PS<2:0> are 000 or 001
;Set Postscaler to
; desired WDT rate
register
(e.g.,
CLRF 1,
Preliminary
EXAMPLE 6-2:
CLRWDT
MOVLW
OPTION
6.3
When the PIC16HV540 is programmed to operate in
the RC oscillator mode, the CLKOUT pin is connected
to the compliment state of TMR0<0>. Use of the pres-
caler rate select bits PSA:PS0 in the OPTION register
will provide for frequencies of CLKIN/8 to CLKIN/1024
on the CLKOUT pin.
EXAMPLE 6-3:
In addition to this mode of operation, TMR0<0> can be
toggled via the bcf and bsf bit type instructions. For this
mode, the T0CS bit in the OPTION register must be set
to 1. This setting configures TMR0 to increment on the
T0CKI pin. To set the CLKOUT pin high, a bcf TMR0,0
instruction is used and to set the CLKOUT pin low, the
bsf TMR0,0 instruction is used. The T0CKI pin should
be pulled high or low to prevent false state changes on
the CLKOUT pin.
1Mhz
2Mhz
3Mhz
4Mhz
Fosc
’xxxx0xxx’
Programmable Clock Generator
PRESCALER SETTING/CLKOUT FREQUENCY
CLKIN/1024
1953 Hz
2930 Hz
3906 Hz
976 Hz
CHANGING PRESCALER
(WDT TIMER0)
2000 Microchip Technology Inc.
;Clear WDT and
;prescaler
;Select TMR0, new
;prescale value and
;clock source
CLKIN/8
125 kHz
250 kHz
375 kHz
500 kHz