SM59R16A2 Datasheet, PDF (25/67 Pages) SyncMOS Technologies,Inc – 8-Bit Micro-controller

SM59R16A2/SM59R08A2
8-Bit Micro-controller
64KB/32KB ISP Flash & 2KB RAM embedded
6.2 Operating registers
The MDU is handled by seven registers, which are memory mapped as special function registers.
The arithmetic unit allows operations concurrently to and independent of the CPU’s activity.
Operands and results registers are MD0 to MD5, and the control register is ARCON.
Any calculation of the MDU will overwrite its operands.
Mnemonic: ARCON
7
6
5
4
3
2
1
MDEF MDOV SLR
SC [4:0]
Address: EFh
0 Reset
00h
MDEF: Multiplication Division Error Flag.
The MDEF is an error flag. The error flag is read only. The error flag indicates
an improperly performed operation (when one of the arithmetic operations has
been restarted or interrupted by a new operation). The error flag mechanism is
automatically enabled with the first write to MD0 and disabled with the final
read instruction from MD3 (multiplication or shift/normalizing) or MD5 (division)
in the third phase.
The error flag is set when:
1. The second phase in process and write access to MDx registers (restart or
interrupt calculations)
The error flag is reset only if:
The second phase finished (arithmetic operation successful completed) and
read access to MDx registers.
MDOV: Multiplication Division Overflow flag. The overflow flag is read only.
The overflow flag is set when:
Divided by zero
Multiplication with a result greater then 0000FFFFh
Start of normalizing if the most significant bit of MD3 is set (MD3.7=1)
The overflow flag is reset when:
Write access to MD0 register (start the first phase)
SLR: Shift direction bit.
SLR = 0 – shift left operation.
SLR = 1 – shift right operation.
SC [4:0]: Shift counter.
When preset with 00000b, normalizing is selected. After normalized, SC[4:0]
contains the number of normalizing shifts performed. When SC[4:0] ≠ 0, shift
operation is started. The number of shifts performed is determined by the
count written to SC [4:0]. SC [4] is MSB and SC[0] is LSB.
Specifications subject to change without notice contact your sales representatives for the most recent information.
ISSFD-M034
25
Ver.B SM59R16A2/SM59R08A2 06/2009