EM78M612
Universal Serial Bus Microcontroller Series
8. Low Pattern Counter Interrupt Conditions If the Pattern Detecting Application function is
enabled, there will be three conditions with which interruption is
generated and the status flag RF[7] is set to 1. Its interrupt vector
is 0X0001.
a) P.60 turns to high, and Pattern Counter value bigger than RB
register value.
b) P.60 stays low, and Pattern Counter value equal 0XFF.
c) P.60 turns to high, and Pattern Counter value bigger than
0XFF.
IOCF is an interrupt mask register which can be set individually bit by bit. While their
respective bit is written to 0, the hardware interrupt will inhibit, that is, the EM78M612 will not
jump to the interrupt vector to execute instructions. But the interrupt status flags still records
the conditions no matter whether the interrupt is masked or not. The interrupt status flags
must be cleared by firmware before leaving the interrupt service routine and enabling
interrupt.
The global interrupt is enabled by the ENI (RETI) instruction and is disabled by the DISI
instruction.
8.8 Pattern Detecting Application (PDA)
8.8.1 Function Description
This function is designed for the serial signal transmission, e.g., the transmission between a
wireless device and its receiver box. The EM78M612 has a built-in Pattern Detecting
Application block that ensures the EM78M612 supports wireless devices, such as receiver
box controller for a wireless mouse.
Pattern Detecting Application (PDA) can calculate the length of one pattern and interrupt the
MCU while the serial signal is transiting from high to low (or vise-versa). Then the MCU
reads the length value from a specified register.
8.8.2 Control Register
RA (High Pattern Counter Register) Default Value: (0B_0000_0000)
7
6
5
4
3
2
1
0
HP.7
HP.6
HP.5
HP.4
HP.3
HP.2
HP.1
HP.0
This register is used in pattern detecting application. If this function is disabled (IOCE[2] = 0),
the PDA function is disabled. RA register is also used as a general-purpose register.
This specification may change without further notice.
2004/4/28 V1.1
30
ELAN [ ELAN MICROELECTRONICS CORP ]
