Oki MSM66591, User Manual

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24-3
MSM66591/ML66592 User's Manual
Chapter 24 RAM Monitor Function
24
24.2 Configuration of Serial Transfer Data
Figure 24-2 shows the format of transfer data (RAM address/ROM address to be set,
RAM address to be read).
The transfer data length is 21 bits. In accordance with the synchronous clock input to
the RMCLK pin, data is transferred LSB first.
The desired RAM address to be read can be set within the range from 0000H to 19FFH
for the MSM66591 and from 0000H to 21FFH for the ML66592. Data can be read from
the set RAM address only if a write operation has been performed. If a read operation is
attempted after an instruction other than a write instruction, such as in the case of a
counter (including ACC, PSW, etc.) whose contents are changed automatically, incor-
rect values may be read.
The ROM address setting range is from 00000H to 1FFFDH for the MSM66591 and
from 0000H to 2FFFDH for the ML66592.
<Description of Each Bit>
[RAM or ROM address reception]
• RAM address field (bit 0 to bit 15: when setting a RAM address)
Sets the RAM address desired to be read.
• ROM address field (bit 0 to bit 17: when setting a ROM address)
Sets the ROM address that determines read timing for the RAM address desired to
be read.
• MODE (bit 18)
If setting a ROM address, set the MODE bit to "1". If setting a RAM address, set to
"0".
• ENABLE (bit 19)
The enable bit specifies whether the addresses that have been set are valid or
invalid. If the enable bit is "1", the addresses that were input are valid and are stored
in each address buffer. If the enable bit is "0", the addresses that were input are
ignored.
• GO (bit 20)
This bit controls operation of the RAM monitor. When the GO bit is "1", the RAM
monitor function starts monitor operation at the set address. When the GO bit is "0",
operation is stopped.
[RAM data transmission]
• RAM data field (bit 0 to bit 15)
Outputs data at the RAM address desired to be read.
[Notes] 1. When setting a RAM address, be sure to set the dummy bits (bit 16 and bit 17)
to "0".
2. The dummy bits (bit 16 to bit 20) in the transmit format of the RAM data desired
to be read always output "0".