P89LV51RD2BA PHILIPS [NXP Semiconductors], P89LV51RD2BA Datasheet - Page 47

• Manufacturer Part Number: P89LV51RD2BA
• Description: 8-bit 80C51 3 V low power 64 kB Flash microcontroller with 1 kB RAM
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
9397 750 14342
Product data
The Watchdog timer function is implemented in module 4 of PCA.
The CCON SFR contains the run control bit for the PCA (CR) and the flags for the
PCA timer (CF) and each module (CCF4:0). To run the PCA the CR bit (CCON.6)
must be set by software. The PCA is shut off by clearing this bit. The CF bit (CCON.7)
is set when the PCA counter overflows and an interrupt will be generated if the ECF
bit in the CMOD register is set. The CF bit can only be cleared by software. Bits 0
through 4 of the CCON register are the flags for the modules (bit 0 for module 0, bit 1
for module 1, etc.) and are set by hardware when either a match or a capture occurs.
These flags can only be cleared by software. All the modules share one interrupt
vector. The PCA interrupt system is shown in
Each module in the PCA has a special function register associated with it. These
registers are: CCAPM0 for module 0, CCAPM1 for module 1, etc. The registers
contain the bits that control the mode that each module will operate in.
The ECCF bit (from CCAPMn.0 where n = 0, 1, 2, 3, or 4 depending on the module)
enables the CCFn flag in the CCON SFR to generate an interrupt when a match or
compare occurs in the associated module (see
PWM (CCAPMn.1) enables the pulse width modulation mode.
The TOG bit (CCAPMn.2) when set causes the CEX output associated with the
module to toggle when there is a match between the PCA counter and the module’s
capture/compare register.
The match bit MAT (CCAPMn.3) when set will cause the CCFn bit in the CCON
register to be set when there is a match between the PCA counter and the module’s
capture/compare register.
The next two bits CAPN (CCAPMn.4) and CAPP (CCAPMn.5) determine the edge
that a capture input will be active on. The CAPN bit enables the negative edge, and
the CAPP bit enables the positive edge. If both bits are set both edges will be enabled
and a capture will occur for either transition.
The last bit in the register ECOM (CCAPMn.6) when set enables the comparator
function.
There are two additional registers associated with each of the PCA modules. They
are CCAPnH and CCAPnL and these are the registers that store the 16-bit count
when a capture occurs or a compare should occur. When a module is used in the
PWM mode these registers are used to control the duty cycle of the output.
Rev. 04 — 02 December 2004
P89LV51RB2/RC2/RD2
8-bit microcontrollers with 80C51 core
Figure
Figure
22.
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
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