ePVP6800
VFD Controller
Bit 3 (PAB)
: Prescaler assignment bit
0/1 ꢂTCC/WDT
When in WDT mode (Bit 3 = 1), the prescaler is cleared by the WDTC and SLEP
instructions. Likewise, when in TCC mode (Bit 3 = 0), the prescaler will can NOT be
cleared by SLEP instructions.
An 8-bit counter is provided as prescaler for the TCC or WDT. The prescaler is
available for the TCC only or for the WDT only at a given time.
An 8 bit counter is made available for TCC or WDT as determined by the status of
Bit 3 (PAB) of the CONT register.
Both TCC and prescaler are cleared each time a write to TCC instruction is
executed. (See the table above for the prescaler ratio under CONT register and
Fig.5 below for the TCC/WDT block diagram.)
Bit 4 (RETBK) : Return value backup control for interrupt routine
0/1 ꢂdisable/enable
When this bit is set to 1, the CPU will store ACC, R3 status, and R5 PAGE 1
automatically after an interrupt is triggered. It will be restored after instruction RETI.
When this bit is set to 0, you need to store ACC, R3, and R5 PAGE 1 in you
program.
Bit 5 (TS)
: TCC signal source
0 ꢂinternal instruction cycle clock
timing = ( 2 / system clock) * prescaler* (256 – count vaule)
1 ꢂ16.384kHz
timing = ( 1 /16.384k) * prescaler * (256 – count vaule)
timing = (2/Fosc) * Prescaler * (256 – count vaule)
Bit 6 (INT)
: INT enable flag
0 ꢂinterrupt masked by DISI or hardware interrupt
1 ꢂinterrupt enabled by ENI/RETI instructions
Bit 7 (P90EG) : Interrupt edge type of P90
0 ꢂP90 interruption source is a rising edge signal.
1 ꢂP90 interruption source is a falling edge signal.
This specification is subject to change without further notice.
11.28.2004 (V123) 19 of 47
ELAN [ ELAN MICROELECTRONICS CORP ]
