UPD75208 NEC, UPD75208 Datasheet - Page 22

• Manufacturer Part Number: UPD75208
• Description: 4-BIT SINGLE-CHIP MICROCOMPUTER
• Manufacturer: NEC

22
5.8
Note
The on-chip FIP controller/driver has the following functions:
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•
•
•
•
•
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Generates the segment and digit signals by automatically reading the display data memory executing DMA
operation.
Can select up to a total of 26 display devices in the range of 9 to 12 segments and 9 to 16 digits.
Can apply the remaining display output as static output.
Can adjust the brightness at 8 levels using the dimmer function.
Can apply key scan operations.
• Generates interrupt at the key scan timing (IRQKS)
• Can generate key scan data output from the segment output pin.
Owns the high-voltage output pin (40 V) which can directly drive the FIP.
• Segment special pins (S0 to S9) : V
• Digit output pins (T0 to T15)
Can incorporate pull-down resistors bit-wise as mask options.
FIP CONTROLLER/DRIVER
The FIP controller/driver can only operate in the high and intermediate-speeds (PCC = 0011B or 0010B) of
the main system clock (SCC.0 = 0). It may cause errors with any other clock or in the standby mode. Thus,
be sure to stop FIP controller operation (DSPM.3 = 0) and then shift the unit to any other clock mode or
the standby mode.
Segment Data Latch (12)
Display Data Memory
(48
Key Scan Registers
(KS0 and KS1)
S0-S9
10
10
4 Bits)
12
Fig. 5-8 FIP Controller/Driver Block Diagram
T15/S10 and
T14/S11
Hige-Voltage Output Buffer
2
2
2
2
: V
Selector
OD
OD
4
T13/PH0-
T10/PH3
Internal Bus
Port H
= 40 V, I
= 40 V, I
4
4
4
OD
OD
Display
Mode
Register
= 3 mA
= 15 mA
4
Digit Signal Generator
T0-T9
Digit
Select
Register
10
10
4
Dimmer
Select
Register
4
V
LOAD
Key Scan
Flag (KSF)
V
PRE
IRQKS
Generation
Signal
PD75208