m37516e6hp Renesas Electronics Corporation., m37516e6hp Datasheet - Page 78

• Manufacturer Part Number: m37516e6hp
• Description: Single-chip 8-bit Cmos Microcomputer
• Manufacturer: Renesas Electronics Corporation.

7516 Group
NOTES ON PROGRAMMING
Processor Status Register
The contents of the processor status register (PS) after a reset are
undefined, except for the interrupt disable flag (I) which is “1.” Af-
ter a reset, initialize flags which affect program execution. In
particular, it is essential to initialize the index X mode (T) and the
decimal mode (D) flags because of their effect on calculations.
Interrupts
The contents of the interrupt request bits do not change immedi-
ately after they have been written. After writing to an interrupt
request register, execute at least one instruction before perform-
ing a BBC or BBS instruction.
Decimal Calculations
• To calculate in decimal notation, set the decimal mode flag (D)
• In decimal mode, the values of the negative (N), overflow (V),
Timers
If a value n (between 0 and 255) is written to a timer latch, the fre-
quency division ratio is 1/(n+1).
Multiplication and Division Instructions
• The index X mode (T) and the decimal mode (D) flags do not af-
• The execution of these instructions does not change the con-
Ports
The contents of the port direction registers cannot be read. The
following cannot be used:
• The data transfer instruction (LDA, etc.)
• The operation instruction when the index X mode flag (T) is “1”
• The addressing mode which uses the value of a direction regis-
• The bit-test instruction (BBC or BBS, etc.) to a direction register
• The read-modify-write instructions (ROR, CLB, or SEB, etc.) to
Use instructions such as LDM and STA, etc., to set the port direc-
tion registers.
Serial I/O
In serial I/O1 (clock synchronous mode), if the receive side is us-
ing an external clock and it is to output the S
transmit enable bit, the receive enable bit, and the S
enable bit to “1.”
Serial I/O1 continues to output the final bit from the T
transmission is completed.
S
sion is completed.
When an external clock is used as synchronous clock in serial
I/O1 or serial I/O2, write transmission data to the transmit buffer
register or serial I/O2 register while the transfer clock is “H.”
Rev.1.01
OUT2
to “1”, then execute an ADC or SBC instruction. After executing
an ADC or SBC instruction, execute at least one instruction be-
fore executing a SEC, CLC, or CLD instruction.
and zero (Z) flags are invalid.
fect the MUL and DIV instruction.
tents of the processor status register.
ter as an index
a direction register.
pin for serial I/O2 goes to high impedance after transmis-
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RDY1
signal, set the
RDY1
X
D pin after
output
A-D Converter
The comparator uses capacitive coupling amplifier whose charge
will be lost if the clock frequency is too low.
Therefore, make sure that f(X
at least on 500 kHz during an A-D conversion.
Do not execute the STP instruction or the WIT instruction during
an A-D conversion.
Instruction Execution Time
The instruction execution time is obtained by multiplying the fre-
quency of the internal clock
execute an instruction.
The number of cycles required to execute an instruction is shown
in the list of machine instructions.
The frequency of the internal clock
high-speed mode.
NOTES ON USAGE
Handling of Source Pins
In order to avoid a latch-up occurrence, connect a capacitor suit-
able for high frequencies as bypass capacitor between power
source pin (V
source pin (V
pin). Besides, connect the capacitor to as close as possible. For
bypass capacitor which should not be located too far from the pins
to be connected, a ceramic capacitor of 0.01 F–0.1 F is recom-
mended.
EPROM Version/One Time PROM Version/
Flash Memory Version
The CNVss pin is connected to the internal memory circuit block
by a low-ohmic resistance, since it has the multiplexed function to
be a programmable power source pin (V
To improve the noise reduction, connect a track between CNVss
pin and Vss pin or Vcc pin with 1 to 10 k
The mask ROM version track of CNVss pin has no operational in-
terference even if it is connected to Vss pin or Vcc pin via a
resistor.
Electric Characteristic Differences Among
Mask ROM, Flash Memory, and One Time
PROM Version MCUs
There are differences in electric characteristics, operation margin,
noise immunity, and noise radiation among mask ROM, flash
memory, and One Time PROM version MCUs due to the differ-
ences in the manufacturing processes.
When manufacturing an application system with the flash memory,
One Time PROM version and then switching to use of the mask
ROM version, perform sufficient evaluations for the commercial
samples of the mask ROM version.
CC
CC
pin) and GND pin (V
pin) and analog power source input pin (AV
IN
by the number of cycles needed to
) in the middle/high-speed mode is
is half of the X
SS
PP
pin) and between power
resistance.
pin) as well.
IN
frequency in
SS