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■ 3.4 Peripheral access protocol and data format in SH2 direct mode

Peripheral access protocol and data format in SH-2 direct mode are shown here.

■ About Peripheral Port Bit Name

The SMPC peripheral port configuration inherits the mega drive peripheral port to maintain compatibility with the mega drive. Therefore, the port bit name is also inherited from the mega drive name. Table 3.22 shows the correspondence between port bit numbers and port bit names. In the rest of this manual, port bit names will be used for explanation.

Table 3.22 Correspondence between port bit number and port bit name 
bit1
D
 Port bit number 
 bit6 
 bit5 
bit4
bit3
bit2
bit0
 
 Port bit name 
 TH 
 TR 
TL
R
L
U

■ Mega-Drive Peripheral ID Calculation Method in SH-2 Direct Mode

Megadrive peripheral ID calculation formula is shown below.
Mega Drive Peripheral ID is represented by 4 bits of ID3 ID2 ID1 ID0. 

 ID3 ＝ R # L (TH = 1)
ID2 ＝ D # U (TH = 1)
ID1 ＝ R # L (TH = 0)
ID0 ＝ D # U (TH = 0)

# Indicates a logical sum (OR).

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