APU0071-002WE-TY Просмотр технического описания (PDF) - Anpec Electronics
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APU0071-002WE-TY Datasheet PDF : 28 Pages
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APU0071
FUNCTION DESCRIPTION
1. SYSTEM INTERFACE
This chip consists of two kinds of interface type with MPU : 4-bit bus and 8-bit bus.
4-bit bus and 8-bit bus is selected by DL bit of function set in the instruction register.
During read or write operation, two 8-bit registers are used. One is the data register (DR); the other is the
instruction register (IR) .
The data register (DR) is used as a temporary data storage place for being written into or read from
DDRAM / CGRAM, target RAM is selected by RAM address setting instruction. Each internal operation,
reading from or writing into RAM, is done automatically.
Thus, after MPU reads DR data, the data in the next DDRAM / CGRAM address is transferred into DR
automatically. Also after MPU writes data to DR, the data in DR is transferred into DDRAM / CGRAM
automatically.
The Instruction register (IR) is used only to store instruction code transferred from MPU.
MPU cannot read data from instruction register.
Table 1. Various kinds of operation according to RS and R / W bits.
RS
R/L
Operation
0
0 Instruction Write operation (MPU Writes Instruction into IR)
0
1 Read Busy flag (DB7) and address counter (DB0 ~ DB6)
1
0 Data Write operation (MPU Writes data into DR)
1
1 Data Read operation (MPU Writes data into DR)
The register selection depends on RS input pin setting in both 4-bit bus mode.
2. BUSY FLAG (BF)
BF = “High” it indicates that the internal operation is being processed. So during this time the next instruc-
tion cannot be accepted. BF can be read, when RS = Low and R / W = High (Read instruction Operation) ,
through DB7 port.
Before exciting the next instruction, be sure that BF is not High.
3. ADDRESS COUNTER (AC)
Address Counter (AC) stores the address of DDRAM / CGRAM that are transferred from IR.
After writing into (reading from) DDRAM / CGRAM data, AC is increased (decreased) by 1 automatically.
When RS = “Low”, and R / W = “High”, AC value can be read through DB0 ~ DB6 ports.
Copyright ANPEC Electronics Corp.
6
Rev. A.07 - FEB., 2002
www.anpec.com.tw
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