PIC16F1937-E/PT Microchip Technology, PIC16F1937-E/PT Datasheet - Page 27

• Manufacturer Part Number: PIC16F1937-E/PT
• Description: 14KB Flash, 512B RAM, 256B EEPROM, LCD, 1.8-5.5V 44 TQFP 10x10x1mm TRAY
• Manufacturer: Microchip Technology
• Series: PIC® XLP™ 16Fr

Specifications of PIC16F1937-E/PT

• 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
• Program Memory Size: 14KB (8K x 14)
• Program Memory Type: FLASH
• 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 ~ 125°C
• Package / Case: 44-TQFP, 44-VQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPENDIX D:
; ************************* TWIST24 ******************************
;
; Purpose of routine is to evaluate
;
;
; X1 =
;
;
; Such as A+B = 2^n
;
; Simplified this formula will then become
;
;
; X1 =
;
;
; Where:
; X1 - is new recursive lowpassed filter value
; X0 - is previous lowpassed filter value
; Y
; A,B are weight factors, if A is large relative to B
; then more emphasis is placed on the average ( filtered ) value.
; If B is large then the latest sample are given more weight.
; ~A is A's bitwise complement
;
;
; X0,X1,Y are 24 bit variables
; A+B = 2^8 = 256 for this routine
;
; By Tony Kübek 2000-05-23, based on routine 'twist.asm' by
; Scott Dattalo ( BTW Thanks for sharing :-) )
;
; ****************************************************************
;
; NewSample = Y ( 4 byte ram, 3 byte data )
; OldFilter = X0 ( 4 byte ram, 3 byte data )
; NewFilter = X1 ( 4 byte ram, 3 byte data )
; FilterWeight = A ( 1 byte ram, how much weight that is placed on old filtered value )
;
; * variables not really needed but used in example *
; FilterCounter = 1 byte, counter to increase step responce.
; UpdateCounter = 1 byte, how many samples between 'global' updates
; AD_NewValue = 3 byte ram, last 24 bit reading from AD/or similar ( copied
;
; AD_DataVal = 3 byte ram, filtered value updated after UpdateCounter samples
; _AD_DataReady = 1 bit, set when AD_DataVal is updated
;
#define UPDATE_COUNT
#define FILTER_WEIGHT
CBLOCK
© 2009 Microchip Technology Inc.
AD_NewValue:3
A*X0 + B*Y
A*X0 + ~A*Y + Y
- is new value
to NewSample, in case AD_NewValue should be used for other purposes )
2^n
---------
A + B
---------------
0x020
24-BIT 256 STEP IIR FILTER MODIFIED FOR ENHANCED PIC12/16
0x20
0x80
; 32 samples between global updates
; filterweight, i.e. 'A' in example above
DS41375A-page 27