PIC16F1937-I/P Microchip Technology, PIC16F1937-I/P Datasheet - Page 23

• Manufacturer Part Number: PIC16F1937-I/P
• Description: IC PIC MCU FLASH 512KX14 40-PDIP
• Manufacturer: Microchip Technology
• Series: PIC® XLP™ 16Fr

Specifications of PIC16F1937-I/P

• Program Memory Type: FLASH
• Program Memory Size: 14KB (8K x 14)
• Package / Case: 40-DIP (0.600", 15.24mm)
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 32MHz
• Connectivity: I²C, LIN, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, LCD, POR, PWM, WDT
• Number Of I /o: 36
• Eeprom Size: 256 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Data Converters: A/D 14x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: PIC16F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 512 B
• Interface Type: EUSART/MI2C/SPI
• Maximum Clock Frequency: 32 MHz
• Number Of Programmable I/os: 36
• Number Of Timers: 5
• Maximum Operating Temperature: + 85 C
• Mounting Style: Through Hole
• 3rd Party Development Tools: 52715-96, 52716-328, 52717-734
• Development Tools By Supplier: PG164130, DV164035, DV244005, DV164005
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 14-ch x 10-bit
• A/d Bit Size: 10 bit
• A/d Channels Available: 14
• Height: 4.95 mm
• Length: 53.21 mm
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 1.8 V
• Width: 14.73 mm
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

MAIN_LOOP
;++++++++++++
;
; TWIST24 - Variable 24 bit lowpass filter, calculates new lowpassed value in NewFilter,
; by weighing previous filtervalue and NewSample according to FilterWeight
; If FilterWeight is large more emphasis is placed on oldfiltered value
; Maximum value for FilterWeight is 255 ( i.e. 8 bit variable ).
; FilterWeight = 0 -> NewFilter = 0/256 of OldFilter + 256/256 of NewSample, i.e no filtering
; FilterWeight = 255 -> NewFilter = 255/256 of OldFilter + 1/256 of NewSample, i.e. full filtering
; NOTE: Previous filtered value should be kept in NewFilter as it is used for next pass.
;
TWIST24
TWIST_GO
© 2009 Microchip Technology Inc.
CLRF
; wait for some data from AD or similar
BTFSS _AD_DataReady
GOTO
; filtered data available
; do whatever needs to be done..
BCF _AD_DataReady
GOTO
; about 252-285 instructions executed ( with global update and copying of new datavalue )
; roufly 57 us at XTAL 20 Mhz
; ! uses FSR !
; Ramp function, uses an extra ram variable FilterCounter that
; increases the FilterWeight until itself zero
; Usage: Initialise to FilterWeight, then a speedier time to target will
; be accomplished (step response). During run, if for any reason an high ramp
; is detected ( or loss of readings ) this could be re-initialized to any
; value equal or less than FilterWeight to achive quicker step responce.
; NOTE : Filterweight must then ALSO be initialized so that the following
; is fulfilled: FilterCounter + FilterWeight = DesiredFilterWeight
MOVF
BTFSC STATUS,Z
GOTO
DECFSZ
INCF
; Copy previous filtered value ( note previous value is multiplied by 256
; i.e. only copy top three bytes of source to lowest three bytes of dest. )
MOVF
MOVWF OldFilter+1
MOVF
MOVWF OldFilter+2
MOVF
MOVWF OldFilter+3
; copy new value from AD to 'local' variable and add it it
FilterWeight
MAIN_LOOP
MAIN_LOOP
FilterCounter,F
TWIST_GO
FilterWeight,F
NewFilter,W
NewFilter+1,W
NewFilter+2,W
FilterCounter,F
; check if data available
; nope
; clear data ready flag
DS41375A-page 23