you may well have but if you think every pic chip is the same then you will be in for a world of hurt . read the data sheet(I remember reading somewhere that USART ignores TRIS, or something...?)
Re: Framing error if I disable transmitter after shift register is empty?
you may well have but if you think every pic chip is the same then you will be in for a world of hurt . read the data sheet(I remember reading somewhere that USART ignores TRIS, or something...?)
Warning I'm not a teacher
Re: Framing error if I disable transmitter after shift register is empty?
Well the carpet is one thing. Even if you just walked the room and returned back to you chair (even worse if it has suspension), then you may well have charged enough to destroy the chips.Originally Posted by Demon
You have to remember to ground yourself just before you touch components or even better have a wrist band to permantly ground your body (through a high value resistor of course).
ESD can destroy just a tiny part of the chip, enough to drive you crazy!
Ioannis
Re: Framing error if I disable transmitter after shift register is empty?
The USART section in the datasheet for your device will tell you if you should set/clear the TRIS bits for the TX/RX pins.Am I supposed to set TRIS as well?
If the chip supports open-drain mode then you just need to setup the TX pin to enable it at startup (ODCONC.6 = 1).
There's no need to set and clear it, and you won't need to enable/disable TXEN anymore either.
Add a pullup to the TX line (you say you already have one), and you can connect all the TX lines from the different pics together now.
If your pic has PPS you'll probably need to set that up too to assign the pin to the UART TXD function.
PPS output functions aren't typically enabled by default.
Re: Framing error if I disable transmitter after shift register is empty?
To be able to add more PICs later on the TX line.
Yup, on RX also. Both are on PIC #1.
(Using 16F18877 for testing)
PIC #1:
Code:#CONFIG __config _CONFIG1, _FEXTOSC_OFF & _RSTOSC_HFINT32 & _CLKOUTEN_OFF & _CSWEN_OFF & _FCMEN_ON __config _CONFIG2, _MCLRE_ON & _PWRTE_OFF & _LPBOREN_OFF & _BOREN_ON & _BORV_LO & _ZCD_OFF & _PPS1WAY_OFF & _STVREN_ON & _DEBUG_OFF __config _CONFIG3, _WDTCPS_WDTCPS_11 & _WDTE_OFF & _WDTCWS_WDTCWS_7 & _WDTCCS_LFINTOSC __config _CONFIG4, _WRT_OFF & _SCANE_available & _LVP_OFF __config _CONFIG5, _CP_OFF & _CPD_OFF #ENDCONFIG include "DT_INTS-14_16F18877.bas" include "ReEnterPBP.bas" ASM INT_LIST macro ; IntSource, Label, Type, ResetFlag? INT_Handler RX_INT, _RXInterrupt, PBP, yes endm INT_CREATE ; Creates the interrupt processor INT_ENABLE RX_INT ; Enables RX interrupts ENDASM DEFINE OSC 32 DEFINE HSER_RCSTA 90h ' Enable serial port & continuous receive DEFINE HSER_TXSTA 24h ' Enable transmit, BRGH = 1 Define HSER_BAUD 115200 DEFINE HSER_CLROERR 1 ' Clear overflow automatically DEFINE HSER_SPBRGH 0 DEFINE HSER_SPBRG 68 BAUDCON.3 = 1 ' Enable 16 bit baudrate generator DEFINE HSER_RXREG PORTC DEFINE HSER_RXBIT 7 DEFINE HSER_TXREG PORTC DEFINE HSER_TXBIT 6 ANSELA = %00000000 ANSELB = %00000000 ANSELC = %00000000 ANSELD = %00000000 ANSELE = %00000000 TRISA = %00000000 TRISB = %00000000 TRISC = %10000000 TRISD = %00000000 TRISE = %00001000 LEDblink var LatB.5 RecvData var BYTE[11] UsartFlag Var byte pause 200 LEDblink = 0 UsartFlag = 0 goto Start RXInterrupt: hserin [ wait("["), STR RecvData\11\"]" ] UsartFlag = 1 @ INT_RETURN Start: ' ODCONC.6 = 0 hserout [ "[X]" ] while TX1STA.1 = 0 ' Check TRMT bit wend ' ODCONC.6 = 1 Mainloop: LEDblink = 1 if UsartFlag = 0 then UsartFlag = 0 endif LEDblink = 0 goto Mainloop end
PIC #2:
Code:#CONFIG __config _CONFIG1, _FEXTOSC_OFF & _RSTOSC_HFINT32 & _CLKOUTEN_OFF & _CSWEN_OFF & _FCMEN_ON __config _CONFIG2, _MCLRE_ON & _PWRTE_OFF & _LPBOREN_OFF & _BOREN_ON & _BORV_LO & _ZCD_OFF & _PPS1WAY_OFF & _STVREN_ON & _DEBUG_OFF __config _CONFIG3, _WDTCPS_WDTCPS_11 & _WDTE_OFF & _WDTCWS_WDTCWS_7 & _WDTCCS_LFINTOSC __config _CONFIG4, _WRT_OFF & _SCANE_available & _LVP_OFF __config _CONFIG5, _CP_OFF & _CPD_OFF #ENDCONFIG include "DT_INTS-14_16F18877.bas" include "ReEnterPBP.bas" ASM INT_LIST macro ; IntSource, Label, Type, ResetFlag? INT_Handler RX_INT, _ReceiveInterrupt, PBP, yes endm INT_CREATE ; Creates the interrupt processor INT_ENABLE RX_INT ; Enables RX interrupts ENDASM DEFINE OSC 32 DEFINE HSER_RCSTA 90h ' Enable serial port & continuous receive DEFINE HSER_TXSTA 24h ' Enable transmit, BRGH = 1 Define HSER_BAUD 115200 DEFINE HSER_CLROERR 1 ' Clear overflow automatically DEFINE HSER_SPBRGH 0 DEFINE HSER_SPBRG 68 BAUDCON.3 = 1 ' Enable 16 bit baudrate generator DEFINE HSER_RXREG PORTC DEFINE HSER_RXBIT 7 DEFINE HSER_TXREG PORTC DEFINE HSER_TXBIT 6 ANSELA = %00000000 ANSELB = %00000000 ANSELC = %00000000 ANSELD = %00000000 ANSELE = %00000000 TRISA = %00000000 TRISB = %00000000 TRISC = %10000000 TRISD = %00000000 TRISE = %00001000 LEDblink var LatD.0 RecvData var BYTE[11] UsartFlag Var byte pause 200 LEDblink = 0 UsartFlag = 0 goto Start ReceiveInterrupt: hserin [ wait("["), STR RecvData\11\"]" ] UsartFlag = 1 @ INT_RETURN Start: Mainloop: LEDblink = 1 if UsartFlag = 1 then ' ODCONC.6 = 0 hserout [ "[Y]" ] while TX1STA.1 = 0 ' Check TRMT bit wend ' ODCONC.6 = 1 UsartFlag = 0 endif LEDblink = 0 GOTO Mainloop end
Results:
Custom DT_INTS-14.bas (IOC, RX, CCPx):
Code:'*************************************************************************** '* Name : DT_INTS-14_16F1885x-7x.bas * '* Author : Darrel Taylor (modified by Demon) * '* Version : 1.15 (8/29/2024) * '* Date : OCT 13, 2009 * '*************************************************************************** '* REV 1.15 Customized for 16F1885xx-7x (IOC, USART-RX, CCPx) * '* REV 1.10 Fixes Duplicate label error when Handlers cross page boundary * '* Fixes error with 16F1's and MPLAB 8.53 (high) * '* REV 1.00 Completely re-written, with optimization and F1 chips in mind * '* REV 0.93 Fixed CMIF and EEIF problem with older PIC's * '* that have the Flags in PIR1 instead of PIR2 * '* Rev 0.92 solves a "Missed Interrupt" and * '* banking switching problem * '*************************************************************************** DEFINE DT_INTS_VERSION 110 DEFINE INTHAND INT_ENTRY ;-- Place a copy of these variables in your Main program ------------------- ;-- The compiler will tell you which lines to un-comment -- ;-- Do Not un-comment these lines -- ;--------------------------------------------------------------------------- ;wsave VAR BYTE $20 SYSTEM ' location for W if in bank0 ;wsave VAR BYTE $70 SYSTEM ' alternate save location for W ' if using $70, comment wsave1-3 ' --- IF any of these three lines cause an error ?? ------------------------ ' Comment them out to fix the problem ---- ' -- Which variables are needed, depends on the Chip you are using -- ;wsave1 VAR BYTE $A0 SYSTEM ' location for W if in bank1 ;wsave2 VAR BYTE $120 SYSTEM ' location for W if in bank2 ;wsave3 VAR BYTE $1A0 SYSTEM ' location for W if in bank3 ' -------------------------------------------------------------------------- ssave VAR BYTE BANK0 SYSTEM ' location for STATUS register psave VAR BYTE BANK0 SYSTEM ' location for PCLATH register fsave VAR BYTE BANK0 SYSTEM ' location for FSR register RetAddr VAR WORD BANK0 INT_Bits VAR BYTE BANK0 Serviced VAR INT_Bits.0 Vars_Saved VAR INT_Bits.1 GIE VAR INTCON.7 PEIE VAR INTCON.6 ASM ifdef PM_USED ; verify MPASM is the assembler "ERROR: DT_INTS does not support the PM assembler, USE MPASM" endif ;--------------------------------------------------------------------------- ifdef ReEnterUsed ifdef ReEnterVersion if (ReEnterVersion < 34) error "Wrong version of ReEnterPBP.bas - Ver 3.4 or higher required endif else error "Wrong version of ReEnterPBP.bas - Ver 3.4 or higher required endif endif ;--------------------------------------------------------------------------- if (BANK0_END == 0x7F) ifdef BANK1_END if (BANK1_END == 0xEF) ; doesn't find 12F683 variable ACCESSRAM = 1 else variable ACCESSRAM = 0 endif else variable ACCESSRAM = 0 endif else variable ACCESSRAM = 0 endif ;--------------------------------------------------------------------------- #define OrChange Or change to wsave BYTE $70 SYSTEM AddWsave macro B if (B == 0) if (ACCESSRAM == 1) error " Add:" wsave VAR BYTE $70 SYSTEM else error " Add:" wsave VAR BYTE $20 SYSTEM endif endif if (B == 1) if (ACCESSRAM == 1) error " Add:" wsave1 VAR BYTE $A0 SYSTEM, OrChange else error " Add:" wsave1 VAR BYTE $A0 SYSTEM endif endif if (B == 2) if (ACCESSRAM == 1) error " Add:" wsave2 VAR BYTE $120 SYSTEM, OrChange else error " Add:" wsave2 VAR BYTE $120 SYSTEM endif endif if (B == 3) if (ACCESSRAM == 1) error " Add:" wsave3 VAR BYTE $1A0 SYSTEM, OrChange else error " Add:" wsave3 VAR BYTE $1A0 SYSTEM endif endif endm #define WsaveE1(B) Chip has RAM in BANK#v(B), but wsave#v(B) was not found. ;#define WsaveE2(B) Uncomment wsave#v(B) in the DT_INTS-14.bas file. #define WsaveCouldBe This chip has access RAM at $70 #define WsaveError(B) error WsaveE1(B) ifndef FSR0L ; not a 16F1 ifndef wsave ; if (ACCESSRAM == 1) error wsave variable not found, AddWsave(0) variable wsave = 0 ; stop further wsave errors ; else ; endif else if (wsave == 0x70) if (ACCESSRAM == 0) error This chip does not have AccessRAM at $70, change to wsave VAR BYTE $20 SYSTEM endif else if (wsave != 0x20) error wsave must be either $20 or $70 endif endif endif ifdef BANK1_START ifndef wsave1 ifdef wsave if (wsave != 0x70) WsaveError(1) AddWsave(1) endif else if (ACCESSRAM == 1) if (wsave != 0x70) WsaveCouldBe endif endif endif endif endif ifdef BANK2_START ifndef wsave2 ifdef wsave if (wsave != 0x70) WsaveError(2) AddWsave(2) endif endif endif endif ifdef BANK3_START ifndef wsave3 ifdef wsave if (wsave != 0x70) WsaveError(3) AddWsave(3) endif endif endif endif endif ENDASM ASM asm = 0 Asm = 0 ASM = 0 pbp = 1 Pbp = 1 PBP = 1 yes = 1 Yes = 1 YES = 1 no = 0 No = 0 NO = 0 ;---[Original DEFINES]------------------------------------------------------ #define ALL_INT INTCON,GIE, INTCON,GIE ;-- Global Interrupts * ; #define IOC_INT INTCON,IOCIF, INTCON,IOCIE ;-- Int On Change ; #define RX_INT PIR1,RCIF, PIE1,RCIE ;-- USART Receive ; #define CCP1_INT PIR1,CCP1IF, PIE1,CCP1IE ;-- CCP1 ; #define CCP2_INT PIR2,CCP2IF, PIE2,CCP2IE ;-- CCP2 ; #define CCP3_INT PIR3,CCP3IF, PIE3,CCP3IE ;-- CCP3 ; #define CCP4_INT PIR3,CCP4IF, PIE3,CCP4IE ;-- CCP4 ; #define CCP5_INT PIR3,CCP5IF, PIE3,CCP5IE ;-- CCP5 #define IOC_INT PIR0,IOCIF, PIE0,IOCIE ;-- Int On Change * #define RX_INT PIR3,RCIF, PIE3,RCIE ;-- USART Receive #define CCP1_INT PIR6,CCP1IF, PIE6,CCP1IE ;-- CCP1 #define CCP2_INT PIR6,CCP2IF, PIE6,CCP2IE ;-- CCP2 #define CCP3_INT PIR6,CCP3IF, PIE6,CCP3IE ;-- CCP3 #define CCP4_INT PIR6,CCP4IF, PIE6,CCP4IE ;-- CCP4 #define CCP5_INT PIR6,CCP5IF, PIE6,CCP5IE ;-- CCP5 ENDASM ASM ;---[Returns the Address of a Label as a Word]------------------------------ GetAddress macro Label, Wout CHK?RP Wout movlw low Label ; get low byte movwf Wout ; movlw High Label ; get high byte MPLAB 8.53 killed high movlw Label >> 8 ; get high byte movwf Wout + 1 endm ;---[find correct bank for a BIT variable]---------------------------------- CHKRP?T macro reg, bit CHK?RP reg endm ;---[This creates the main Interrupt Service Routine (ISR)]----------------- INT_CREATE macro local OverCREATE L?GOTO OverCREATE INT_ENTRY ifndef FSR0L if (CODE_SIZE <= 2) movwf wsave ; 1 copy W to wsave register swapf STATUS,W ; 2 swap status reg to be saved into W clrf STATUS ; 3 change to bank 0 movwf ssave ; 4 save status reg to a bank 0 register movf PCLATH,W ; 5 move PCLATH reg to be saved into W reg movwf psave ; 6 save PCLATH reg to a bank 0 register endIF movf FSR,W ; 7 move FSR reg to be saved into W reg movwf fsave ; 8 save FSR reg to a bank 0 register else banksel 0 ; BANK 0 for F1 chips endif variable PREV_BANK = 0 MOVE?CT 0, _Vars_Saved List_Start ifdef LoopWhenServiced MOVE?CT 0, _Serviced ; indicate nothing has been serviced endif INT_LIST ; Expand the users list of interrupt handlers ; INT_LIST macro must be defined in main program ifdef LoopWhenServiced BIT?GOTO 1, _Serviced, List_Start endif ifdef ReEnterUsed ; if ReEnterPBP.bas was included CHKRP?T _Vars_Saved btfss _Vars_Saved ; if PBP system vars have been saved goto INT_EXIT L?GOTO _RestorePBP ; Restore PBP system Vars endif INT_EXIT variable PREV_BANK = 0 ifndef FSR0L ; if chip is not an F1 - restore context clrf STATUS ; BANK 0 movf fsave,W ; Restore the FSR reg movwf FSR movf psave,w ; Restore the PCLATH reg movwf PCLATH swapf ssave,w ; Restore the STATUS reg movwf STATUS swapf wsave,f swapf wsave,w ; Restore W reg endif retfie ; Exit the interrupt routine ;----------------------------- LABEL?L OverCREATE bsf INTCON, 6 ; Enable Peripheral interrupts bsf INTCON, 7 ; Enable Global interrupts endm ENDASM ASM ;---[Add an Interrupt Source to the user's list of INT Handlers]------------ #INT_HANDLER macro FlagReg,FlagBit, EnableReg,EnableBit, Label, Type,Reset list local AfterSave, AfterUserRoutine, NoInt ifdef FlagBit CHK?RP EnableReg btfss EnableReg, EnableBit ; if the INT is enabled goto NoInt CHK?RP FlagReg btfss FlagReg, FlagBit ; and the Flag set? goto NoInt ifdef LoopWhenServiced MOVE?CT 1, _Serviced endif if (Type == PBP) ; If INT handler is PBP ifdef ReEnterUsed btfsc _Vars_Saved goto AfterSave GetAddress AfterSave, _RetAddr L?GOTO _SavePBP ; Save PBP system Vars LABEL?L AfterSave else error ReEnterPBP must be INCLUDEd to use PBP type interrupts endif endif GetAddress AfterUserRoutine, _RetAddr ; save return address L?GOTO Label ; goto the users INT handler LABEL?L AfterUserRoutine if (Reset == YES) CHK?RP FlagReg bcf FlagReg, FlagBit ; reset flag (if specified) endif else INT_ERROR "INT_Handler" endif NoInt banksel 0 PREV_BANK = 0 endm ;----------------------------------- #define INT_HANDLER(FlagReg,FlagBit, EnableReg,EnableBit, Label, Type,Reset) #INT_HANDLER FlagReg,FlagBit, EnableReg,EnableBit, Label, Type,Reset ifndef INT_Handler #define INT_Handler(FlagReg,FlagBit, EnableReg,EnableBit, Label, Type,Reset) #INT_HANDLER FlagReg,FlagBit, EnableReg,EnableBit, Label, Type,Reset #define int_handler(FlagReg,FlagBit, EnableReg,EnableBit, Label, Type,Reset) #INT_HANDLER FlagReg,FlagBit, EnableReg,EnableBit, Label, Type,Reset #define Int_Handler(FlagReg,FlagBit, EnableReg,EnableBit, Label, Type,Reset) #INT_HANDLER FlagReg,FlagBit, EnableReg,EnableBit, Label, Type,Reset #define Int_handler(FlagReg,FlagBit, EnableReg,EnableBit, Label, Type,Reset) #INT_HANDLER FlagReg,FlagBit, EnableReg,EnableBit, Label, Type,Reset #define int_Handler(FlagReg,FlagBit, EnableReg,EnableBit, Label, Type,Reset) #INT_HANDLER FlagReg,FlagBit, EnableReg,EnableBit, Label, Type,Reset endif ;---[Returns from a "goto" subroutine]--------(RetAddr must be set first)--- #INT_RETURN macro CHK?RP _RetAddr movf _RetAddr + 1, W ; Set PCLATH with top byte of return address movwf PCLATH movf _RetAddr, W ; Go back to where we were movwf PCL endm ;_____________________________ #define INT_RETURN #INT_RETURN ifndef INT_Return #define INT_Return #INT_RETURN #define int_return #INT_RETURN #define Int_Return #INT_RETURN #define Int_return #INT_RETURN #define int_Return #INT_RETURN endif ;----[Display not found error]---------------------------------------------- INT_ERROR macro From error From - Interrupt Flag ( FlagReg,FlagBit ) not found. endm ;---[Enable an interrupt source]-------------------------------------------- ifndef INT_ENABLECLEARFIRST #define INT_ENABLECLEARFIRST 1 ; default to Clear First endif ; use DEFINE INT_ENABLECLEARFIRST 0 to NOT clear First #INT_ENABLE macro FlagReg, FlagBit, EnableReg, EnableBit ifdef FlagBit ifdef INT_ENABLECLEARFIRST if (INT_ENABLECLEARFIRST == 1) ; if specified MOVE?CT 0, FlagReg, FlagBit ; clear the flag first endif endif MOVE?CT 1, EnableReg, EnableBit ; enable the INT source else INT_ERROR "INT_ENABLE" endif endm ;_____________________________ #define INT_ENABLE(FlagReg, FlagBit, EnableReg, EnableBit) #INT_ENABLE FlagReg, FlagBit, EnableReg, EnableBit ifndef INT_Enable #define INT_Enable(FlagReg, FlagBit, EnableReg, EnableBit) #INT_ENABLE FlagReg, FlagBit, EnableReg, EnableBit #define int_enable(FlagReg, FlagBit, EnableReg, EnableBit) #INT_ENABLE FlagReg, FlagBit, EnableReg, EnableBit #define Int_Enable(FlagReg, FlagBit, EnableReg, EnableBit) #INT_ENABLE FlagReg, FlagBit, EnableReg, EnableBit #define Int_enable(FlagReg, FlagBit, EnableReg, EnableBit) #INT_ENABLE FlagReg, FlagBit, EnableReg, EnableBit #define int_Enable(FlagReg, FlagBit, EnableReg, EnableBit) #INT_ENABLE FlagReg, FlagBit, EnableReg, EnableBit endif ;---[Disable an interrupt source]------------------------------------------- #INT_DISABLE macro FlagReg, FlagBit, EnableReg, EnableBit ifdef FlagBit MOVE?CT 0, EnableReg, EnableBit ; disable the INT source else INT_ERROR "INT_DISABLE" endif endm ;_____________________________ #define INT_DISABLE(FlagReg, FlagBit, EnableReg, EnableBit) #INT_DISABLE FlagReg, FlagBit, EnableReg, EnableBit ifndef INT_Disable #define INT_Disable(FlagReg, FlagBit, EnableReg, EnableBit) #INT_DISABLE FlagReg, FlagBit, EnableReg, EnableBit #define int_disable(FlagReg, FlagBit, EnableReg, EnableBit) #INT_DISABLE FlagReg, FlagBit, EnableReg, EnableBit #define Int_Disable(FlagReg, FlagBit, EnableReg, EnableBit) #INT_DISABLE FlagReg, FlagBit, EnableReg, EnableBit #define Int_disable(FlagReg, FlagBit, EnableReg, EnableBit) #INT_DISABLE FlagReg, FlagBit, EnableReg, EnableBit #define int_Disable(FlagReg, FlagBit, EnableReg, EnableBit) #INT_DISABLE FlagReg, FlagBit, EnableReg, EnableBit endif ;---[Clear an interrupt Flag]----------------------------------------------- #INT_CLEAR macro FlagReg, FlagBit, EnableReg, EnableBit ifdef FlagBit MOVE?CT 0, FlagReg, FlagBit ; clear the flag else INT_ERROR "INT_CLEAR" endif endm ;_____________________________ #define INT_CLEAR(FlagReg, FlagBit, EnableReg, EnableBit) #INT_CLEAR FlagReg, FlagBit, EnableReg, EnableBit ifndef INT_Clear #define INT_Clear(FlagReg, FlagBit, EnableReg, EnableBit) #INT_CLEAR FlagReg, FlagBit, EnableReg, EnableBit #define int_clear(FlagReg, FlagBit, EnableReg, EnableBit) #INT_CLEAR FlagReg, FlagBit, EnableReg, EnableBit #define Int_Clear(FlagReg, FlagBit, EnableReg, EnableBit) #INT_CLEAR FlagReg, FlagBit, EnableReg, EnableBit #define Int_clear(FlagReg, FlagBit, EnableReg, EnableBit) #INT_CLEAR FlagReg, FlagBit, EnableReg, EnableBit #define int_Clear(FlagReg, FlagBit, EnableReg, EnableBit) #INT_CLEAR FlagReg, FlagBit, EnableReg, EnableBit endif ENDASM
Last edited by Demon; - 25th September 2024 at 21:09.
My Creality Ender 3 S1 Plus is a giant paperweight that can't even be used as a boat anchor, cause I'd be fined for polluting our waterways with electronic devices.
Not as dumb as yesterday, but stupider than tomorrow!
Re: Framing error if I disable transmitter after shift register is empty?
I've misunderstood/misinterpreted the data sheet before.Seriously, I read the EUSART section and my eyes gloss over when they start making distinctions between half-duplex, full-duplex, synchronous, asynchronous...)
Something like..?
TRISC.7=1
ODCONC.6 = 1
Loop:
TX, RX, rinse repeat
I would have thought you need to reset ODCONC.6 to "standard push/pull"...? (Possible example of not always understanding what the datasheet "means").
Yes, I figured that much. There's just so many peripherals available (coming from a guy that started with a 16F628).
EDIT: I just rechecked the EUSART section (starts at page 543), and they never mention ODCON (last occurence is at page 233).
The datasheet says very little about ODCON:
Last edited by Demon; - 25th September 2024 at 21:28.
My Creality Ender 3 S1 Plus is a giant paperweight that can't even be used as a boat anchor, cause I'd be fined for polluting our waterways with electronic devices.
Not as dumb as yesterday, but stupider than tomorrow!
Re: Framing error if I disable transmitter after shift register is empty?
An open-drain or open-collector output pin is driven by a single transistor, which pulls the pin to only one voltage (generally, to ground). When the output device is off, the pin is left floating (open, or hi-z). A common example is an n-channel transistor which pulls the signal to ground when the transistor is on or leaves it open when the transistor is off.
Open-drain refers to such a circuit implemented in FET technologies because the transistor’s drain terminal is connected to the output; open-collector means a bipolar transistor’s collector is performing the function.
When the Open-drain transistor is off, the signal line is free to be driven low by another device, it generally will be pulled up by a resistor. The resistor prevents an undefined, floating state.
Warning I'm not a teacher
Members who have read this thread : 10You do not have permission to view the list of names.
Posting Permissions
Reply With Quote
Bookmarks