Electronic Components Datasheet Search |
|
PIC18F2680 Datasheet(PDF) 7 Page - Microchip Technology |
|
PIC18F2680 Datasheet(HTML) 7 Page - Microchip Technology |
7 / 14 page © 2007 Microchip Technology Inc. DS80202G-page 7 PIC18F2585/2680/4585/4680 20. Module: EUSART When performing back-to-back transmission in 9-bit mode (TX9D bit in the TXSTA register is set), an ongoing transmission’s timing can be corrupted if the TX9D bit (for the next transmis- sion) is not written immediately following the setting of TXIF. This is because any write to the TXSTA register results in a reset of the Baud Rate Generator which will effect any ongoing transmission. Work around Load TX9D just after TXIF is set, either by polling TXIF or by writing TX9D at the beginning of the Interrupt Service Routine, or only write to TX9D when a transmission is not in progress (TRMT = 1). Date Codes that pertain to this issue: All engineering and production devices. 21. Module: Timer1/Timer3 When Timer1/Timer3 is operating in 16-bit mode and the prescale setting is not 1:1, a write to the TMR1H/TMR3H Buffer registers may lengthen the duration of the period between the increments of the timer for the period in which TMR1H/TMR3H was written. It does not change the actual prescale value. Work around Do not write to TMR1H/TMR3H while Timer1/ Timer3 is running, or else write to TMR1L/TMR3L immediately following a write to TMR1H/TMR3H. Do not write to TMR1H/TMR3H and then wait for another event before also updating TMR1L/TMR3L. Date Codes that pertain to this issue: All engineering and production devices. 22. Module: EUSART The EUSART auto-baud feature may periodically measure the incoming baud rate incorrectly. The rate of incorrect baud rate measurements will depend on the frequency of the incoming synchronization byte and the system clock frequency. Work around None. Date Codes that pertain to this issue: All engineering and production devices. 23. Module: EUSART In rare situations, one or more extra zero bytes have been observed in a packet transmitted by the module operating in Asynchronous mode. The actual data is not lost or corrupted, only unwanted (extra) zero bytes are observed in the packet. This situation has only been observed when the contents of the transmit buffer TXREG are trans- ferred to the TSR during the transmission of a Stop bit. For this to occur, three things must happen in the same instruction cycle: • TXREG is written to, • the baud rate counter overflows (at the end of the bit period), and • a Stop bit is being transmitted (shifted out of TSR). Work around If possible, do not use the module’s double buffer capability. Instead, load the TXREG register when the TRMT bit (TXSTA<1>) is set, indicating the TSR is empty. If double-buffering is used and back-to-back transmission is performed, then load TXREG immediately after TXIF is set or wait 1-bit time after TXIF is set. Both solutions prevent writing TXREG while a Stop bit is transmitted. Note that TXIF is set at the beginning of the Stop bit transmission. If transmission is intermittent, then do the following: • Wait for the TRMT bit to be set before loading TXREG. • Alternatively, use a free timer resource to time the baud period. Set up the timer to overflow at the end of the Stop bit, then start the timer when you load the TXREG. Do not load the TXREG when timer is about to overflow. Date Codes that pertain to this issue: All engineering and production devices. |
Similar Part No. - PIC18F2680 |
|
Similar Description - PIC18F2680 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |