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■ Port setting for acquiring Megadrive peripheral ID

Table 3.23 shows the port direction register settings when acquiring a Megadrive peripheral ID. Set the port direction as follows, read RLDU when TH = 1 and RLDU when TH = 0, and calculate the megadrive peripheral ID using the above formula.
Please read R, L, D, U after 2μS after TH change.

Table 3.23 Port Direction Register Settings when Obtaining Megadrive Peripheral ID 
 Port bit name 
 TH 
 TR 
TL
R
L
D
U
 
 Port direction 
 Set to output 
 input Set

■ Peripheral interface protocol

There are three types of peripheral interface protocols. The following is an overview of each interface protocol and supported peripherals.

TH control method

The TH control method interface protocol uses TR, TL, R, L, D, U when TH = 1, and TR, TL, R, L, D, U when TH = 0. The method to acquire. Peripherals supporting this protocol include Megadrive 3 button PAD and Megadrive 6 button PAD.

TH, TR control method

TH, TR control method The interface protocol is a method for acquiring R, L, D, U data with four bit patterns of TH and TR. Peripherals supporting this protocol include the Saturn standard PAD.

3-wire handshake method

The 3-wire handshake method sends SEL (select) peripherals with TH = 0 and sends REQ (data request) from TR. Signal). In this way, the 3-wire handshake method is a method of acquiring data while checking the status with a 3-wire control signal. Peripherals supporting this protocol include Sega Tap, Sega Mouse, Saturn Analog Joystick, Saturn Keyboard, and Saturn 6P Multi Tap.

■ Megadrive peripheral ID for each peripheral

Table 3.24 shows the mega drive peripheral ID for each peripheral.

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