Function - Casio BN-10 Service Manual & Parts List

3. When battery voltage becomes to be about 2.1 V, BLD1 terminal voltage becomes to be about 0 V
and the low battery message appears even if AC Adapter is used.
4. When battery voltage becomes to be about 1.6 V, BLD2 terminal voltage becomes to be about 0 V
and the power is forced to be turned off to prevent the corruption of memory even if AC Adapter is
used.
5. When AC Adapter voltage becomes to be about 2~3 V instantly and suddenly, BLD2 terminal
voltage becomes to be about 0 V and the power is forced to be turned off.
6. When adapter output voltage becomes to be about 4.5 V, P1 terminal voltage becomes to be
about 0 V, and the power is force to be turned off.
7. The thermal compensation is set to VLCO voltage circuit for LCD using a thermistor (TH).
When ambient temperature becomes low, LCD display becomes dimmer. At this time, VLCO
terminal voltage becomes higher by a thermistor (TH), and then LCD display becomes lighter.
8. FUSE (F601) adjacent to the battery (F601) will be cut off with current of 1A for over 2 seconds.
9. If batteries are not loaded or battery power is low, BLD2 terminal becomes to be about 0 V even
if AC Adapter is used. Therefore, BN Unit power is not turned on or is forced to be turned power
off as described to the page 15.

9-3. Function

Refer to 8. LSI PIN FUNCTION, 9-1. Block Diagram and 10. SCHEMATIC DIAGRAMS.
9-3-1. Memory
LSI303 is Static RAM for operation, and not for user with BN Unit itself, but for user concerning MO-
DEM BW-100.
User's data are saved in flash ROM (LSI304 (LSI304 and LSI306 with BN-20)) with BN Unit itself, and
saved in flash ROM (LSI308) concerning MODEM BW-100.
And LSI301 is a mask ROM for operation.
Data saved in a flash ROM are not deleted even if power is not supplied. Therefore, the lithium battery
for memory backup is not necessary with BN Unit. It is easy to write data using the flash ROM like
RAM. And the overall deletion of data is performed instantly using the flash ROM different from EEPROM.
LSI308 is a flash ROM for OS program.
Data for OPERATION CHECK are saved in this LSI308 also.
NVRAM (Non Volatile RAM) are set interior TAB LSI (LSI4, LSI5) for driving LCD.
Therefore, the display made before battery replacement appears again after battery replacement.
9-3-2. P Key and RESET Key
Pressing P Key, CPU, Gate array and other devices are forced to be initialized using the circuit for
RESET (RESET by hardware) even if power is turned off.
On the other hand, pressing RESET Key, CPU, Gate array and other devices are forced to be initial-
ized using the software because RESET Key is connected to NMI (Non-Maskable Interrupt) terminal.
This RESET by software can be performed while turning power on as described to the page 16.
If any malfunctions or (and) abnormal symptoms exist even after this RESET operation by software,
try to initialize CPU pressing P Key (RESET by hardware).
9-3-2. Line receiver/ driver IC (IC501)
Miss data transfer is often occurred by long wire data transfer lines and rapid data transfer without a
line receiver/ driver. Data transfer speed is 38400 b.p.s. (MAX.) with BN Unit.
Data transfer speed of CASIO Digital Diary prior BN Unit is 9600 b.p.s..
So the high speed line receiver/ driver IC (IC501) is necessary with BN Unit.
This IC is satisfied with electrical requirement of EIA-232E and CCITT V.28.
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