E202075_HD404889 Datasheet, PDF (154/202 Pages) Renesas Technology Corp – Low-Voltage AS Microcomputers with On-Chip LCD Circuit

HD404889/HD404899/HD404878/HD404868 Series
terminal. If power source noise is noticed, insert an appropriate capacitor between the GND power
sources depending on the noise generated. In case of high frequency noise , insert a capacitor of low
inductance.
(d) For stable writing and reading operation, insert the IC into the socket adapter and check the input
waveform, timing and noise near the R/W, CS, address and data terminals. Particularly, since recent
ICs have increased in speed, caution should be exercised against the noise to the power source or
address due to crosstalk from the output data terminal. To avoid these problems, inserting a low
inductance capacitor between the GND and power source or inserting a damping resistance to the output
data terminal is effective.
(e) Particularly, when a multiple PROM writer is used, perform above items (a), (b), (c), and (d) assuming
all ICs inserted into the socket adapter.
(f) In the case of a multiple PROM writer, when an unacceptable result is noticed during a blank check
performed to prevent erroneous writing due to improper electrical connection of the power source, etc.,
rewriting is impossible unless every writing process can be stopped. Therefore, the potential increases
due to erroneous writing because of improper connection. Be sure to check the electrical connection
between the PROM writer and socket adapter and IC.
(g) If any abnormality is noticed while checking a written program, consult our technical staff.
2. Programming of Built-in programmable ROM
The MCU can stop its function as an MCU in PROM mode for programming the built-in PROM.
PROM mode is set by driving the RESET, M₀, and M₁ pins low (or by driving the RESET and M₀ pins low
in the HD4074869), and driving the TEST pin to the V_PP level.
Writing and reading specifications of the PROM are the same as those for the commercial EPROM27256.
Using a socket adapter for specific use of each product, programming is possible with a general-purpose
PROM writer.
Since an instruction of the HMCS400 series is 10 bits long, a conversion circuit is incorporated to adapt the
general-purpose PROM writer. This circuit splits each instruction into five lower bits and five higher bits
to write from or read to two addresses. This enables use of a general-purpose PROM. For instance, to
write to a 16kword of built-in PROM writer with a general-purpose PROM, specify 32kbyte address
($0000-$7FFF). An example of PROM memory map is shown in figure 95.
Notes:
1. When programming with a PROM writer, set up each ROM size to the address given in table 30. If it is
programmed erroneously to an address given in table 30 or later, check of writing of PROM may
become impossible. Particularly, caution should be exercised in the case of a plastic package since
reprogramming is impossible with it. Set the data in unused addresses to $FF.
2. If the indexes of the PROM writer socket, socket adapter and product are not aligned precisely, the
product may break down due to overcurrent. Be sure to check that they are properly set to the writer
before starting the writing process.
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