PIC16C55X, EPROM-Based 8-Bit CMOS MCU Data Sheet

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PIC16C55XTABLE 5-1:PORTA FUNCTIONSName Bit #BufferTypeFunctionRA0 bit0 ST Bi-directional I/O port.RA1 bit1 ST Bi-directional I/O port.RA2 bit2 ST Bi-directional I/O port.RA3 bit3 ST Bi-directional I/O port.RA4/T0CKI bit4 ST Bi-directional I/O port or external clock input for TMR0. Output is opendrain type.Legend: ST = Schmitt Trigger inputTABLE 5-2:SUMMARY OF REGISTERS ASSOCIATED WITH PORTAAddress Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0Value onPORValue onAll Other Resets05h PORTA — — — RA4 RA3 RA2 RA1 RA0 ---x xxxx ---u uuuu85h TRISA — — — TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 ---1 1111 ---1 1111Legend: — = Unimplemented locations, read as ‘0’x = unknownu = unchangedNote: Shaded bits are not used by PORTA.DS40143C-page 24 Preliminary © 1998 Microchip Technology Inc.
PIC16C55X5.2 PORTB and TRISB RegistersPORTB is an 8-bit wide bi-directional port. Thecorresponding data direction register is TRISB. A '1' inthe TRISB register puts the corresponding output driverin a high impedance mode. A '0' in the TRISB registerputs the contents of the output latch on the selectedpin(s).Reading PORTB register reads the status of the pins,whereas writing to it will write to the port latch. All writeoperations are read-modify-write operations. So a writeto a port implies that the port pins are first read, thenthis value is modified and written to the port data latch.Each of the PORTB pins has a weak internal pull-up(≈200 µA typical). A single control bit can turn on all thepull-ups. This is done by clearing the RBPU(OPTION) bit. The weak pull-up is automaticallyturned off when the port pin is configured as an output.The pull-ups are disabled on Power-on Reset.Four of PORTB’s pins, RB7:RB4, have an interrupt onchange feature. Only pins configured as inputs cancause this interrupt to occur (i.e., any RB7:RB4 pinconfigured as an output is excluded from the interrupton change comparison). The input pins (of RB7:RB4)are compared with the old value latched on the lastread of PORTB. The “mismatch” outputs of RB7:RB4are OR’ed together to generate the RBIF interrupt (flaglatched in INTCON). This interrupt can wake thedevice from SLEEP. The user, in the interrupt serviceroutine, can clear the interrupt in the following manner:a) Any read or write of PORTB. This will end themismatch condition.b) Clear flag bit RBIF.A mismatch condition will continue to set flag bit RBIF.Reading PORTB will end the mismatch condition, andallow flag bit RBIF to be cleared.This interrupt on mismatch feature, together withsoftware configurable pull-ups on these four pins alloweasy interface to a key pad and make it possible forwake-up on key-depression. (See AN552 in theMicrochip Embedded Control Handbook.)Note:If a change on the I/O pin should occur when theread operation is being executed (start of the Q2cycle), then the RBIF interrupt flag may notget set.The interrupt on change feature is recommended forwake-up on key depression operation and operationswhere PORTB is only used for the interrupt on changefeature. Polling of PORTB is not recommended whileusing the interrupt on change feature.FIGURE 5-3:BLOCK DIAGRAM OF RB7:RB4 PINSRBPU (1)VDDData busWR PortBWR TRISBData LatchD QCKTRIS LatchD QCK QVDDPNVSSPTTLInputBufferweakpull-upSTBufferVDDVSSI/OpinSet RBIFRD TRISBRD PortBLatchQ DENFrom otherQRB7:RB4 pinsRB7:RB6 in serial programming modeENDRD Port BNote 1: TRISB = 1 enables weak pull-up if RBPU = '0'(OPTION).© 1998 Microchip Technology Inc. Preliminary DS40143C-page 25
Page 4 and 5: PIC16C55XNOTES:DS40143C-page 4 Prel
Page 6 and 7: PIC16C55XTABLE 1-1:PIC16C55X FAMILY
Page 8 and 9: PIC16C55XNOTES:DS40143C-page 8 Prel
Page 10: PIC16C55XFIGURE 3-1: BLOCK DIAGRAMD
Page 15: PIC16C55X4.2.2 SPECIAL FUNCTION REG
Page 18 and 19: PIC16C55X4.2.2.3 INTCON REGISTERThe
Page 20 and 21: PIC16C55X4.3 PCL and PCLATHThe prog
Page 22 and 23: PIC16C55XNOTES:DS40143C-page 22 Pre
Page 26 and 27: PIC16C55XFIGURE 5-4:BLOCK DIAGRAM O
Page 30 and 31: PIC16C55XFIGURE 6-3: TIMER0 TIMING:
Page 32 and 33: PIC16C55X6.3 PrescalerAn 8-bit coun
Page 36 and 37: PIC16C55X7.1 Configuration BitsThe
Page 38 and 39: PIC16C55X7.2.3 EXTERNAL CRYSTAL OSC
Page 40 and 41: PIC16C55X7.4 Power-on Reset (POR),
Page 42 and 43: PIC16C55XTABLE 7-5:INITIALIZATION C
Page 44 and 45: PIC16C55XFIGURE 7-11:EXTERNAL POWER
Page 46 and 47: PIC16C55X7.5.1 RB0/INT INTERRUPTAn
Page 48 and 49: PIC16C55XFIGURE 7-14:WATCHDOG TIMER
Page 50 and 51: PIC16C55X7.9 Code ProtectionIf the
Page 52 and 53: PIC16C55XTABLE 8-2:Mnemonic,Operand
Page 54 and 55: PIC16C55XBCFBit Clear fSyntax: [ la
Page 56 and 57: PIC16C55XCLRWDTSyntax:Operands:Oper
Page 58 and 59: PIC16C55XIORWFInclusive OR W with f
Page 60 and 61: PIC16C55XRETURN Return from Subrout
Page 62 and 63: PIC16C55XSWAPFSwap Nibbles in fSynt
Page 64 and 65: PIC16C55X9.6 SIMICE Entry-Level Har
Page 66 and 67: PIC16C55X9.16 KEELOQ ® Evaluation
Page 70 and 71: PIC16C55XTABLE 10-1:CROSS REFERENCE
Page 72 and 73: PIC16C55X10.2 DC CHARACTERISTICS: P
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PIC16C55X10.3 DC CHARACTERISTICS: P
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PIC16C55X10.5 Timing Diagrams and S
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PIC16C55XFIGURE 10-4:RESET, WATCHDO
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PIC16C55XNOTES:DS40143C-page 80 Pre
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PIC16C55XPackage Type:K04-010 18-Le
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PIC16C55XPackage Type:K04-051 18-Le
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PIC16C55XPrescaler ................
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PIC16C55XREADER RESPONSEIt is our i
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PIC16C55X, EPROM-Based 8-Bit CMOS MCU Data Sheet

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