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116 lines
4.8 KiB
Plaintext
116 lines
4.8 KiB
Plaintext
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-------------------------------------------------- ----------------------------
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SCSI Target Emulator RaSCSI for Raspberry Pi
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Powered by XM6 TypeG Technology.
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Copyright (C) 2016-2020 GIMONS
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-------------------------------------------------- ----------------------------
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□ Necessity of conversion board
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SCSI divides 5V at 220Ω and 330Ω at TTL level (in the case of passive terminator)
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As a result, the state where a voltage of less than 3 V is applied to each signal line becomes a steady state (signal-wise negate)
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It has become.
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Initiator side or target side tries to assert signal (=0V)
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Then, a total current of 5000÷220×2=45mA flows from both terminators.
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If you look at the data sheet of MB89352 which is the SCSI controller of X68000,
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The current is Iol48mA).
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The RPI GPIO cannot absorb such a large sink current. Electrically secure connection
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To do this, it is necessary to make a conversion board with a general-purpose logic IC. General logic
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It is an open collector such as 74LS06 or 07 that can withstand a sink current of 48 mA with IC.
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Use the high power type.
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The author does basic SCSI direction control with 74HC541×3,74HC126×1,74HC04×1
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I tried to build a circuit to drive the bus using 74LS07 × 3 and it works without problems
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I confirmed that.
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If you use 74LS641-1 which is a derivative of 74LS641, you can configure the circuit simply.
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Would be Unlike normal products, the sink current is compatible with 48 mA, so it is necessary to use 74LS07
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there is no. But availability is not so good.
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□ Circuit board of conversion board
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The circuit design is put in the same folder.
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・Target.png
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Conversion board circuit diagram for using SCSI target mode. It is a basic function
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If you want to emulate HDD or MO, you can make something equivalent to this circuit diagram.
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Would be It also uses the fewest GPIO pins.
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If you do not change the pin assignment, it will be included in the standard directory of RaSCSI
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It is possible to use the binary.
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・Fullspec.png
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It is a conversion board circuit diagram that can use SCSI target mode and initiator mode.
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All 74LS641-1 direction control is performed from RaSCSI, so use 3 extra GPIO pins
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I will do it.
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Customize pin assignments to PIN_TAD, PIN_IND, PIN_DTD respectively
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Now you need to set 6,7,8 and compile. Pin assigned
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See Customization.
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□ How to get existing ones
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Recently, you have created a conversion board for RaSCSI mainly through the Twitter area.
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There are people who are. Introducing here
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Is omitted. The timing is undecided, but we plan to distribute the official version for a fee.
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□ Customize pin assignment
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The signal control logic and pin assignment of GPIO are defined in gpiobus.h.
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As a customization example, the following two conversion board definition examples are prepared in gpiobus.h.
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Compiled binaries are also included in the distribution.
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・Aibomu version
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・GAMERnium version
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□ How to customize
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-This is a message when starting up RaSCSI.
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CONNECT_DESC
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・Select the signal control mode.
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SIGNAL_CONTROL_MODE
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0: SCSI logical specification
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Conversion board using 74LS641-1 etc. directly connected or published on HP
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Arthurt: 0V
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Negative: Open collector output (disconnect from bus)
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1: Negative logic specification (when using the conversion board for negative logic -> SCSI logic)
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There are no conversion boards with this specification at this time
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Arthurt: 0V -> (CONVERT) -> 0V
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Negative: 3.3V -> (CONVERT) -> Open collector output
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2: Positive logic specification (when using the conversion board for positive logic -> SCSI logic)
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RaSCSI Adapter Rev.C @132sync etc.
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Arthurt: 3.3V -> (CONVERT) -> 0V
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Negative: 0V -> (CONVERT) -> Open collector output
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・Control signal pin assignment
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PIN_ACT: The pin number of the signal that indicates the status that the SCSI command is being processed.
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PIN_ENB: Pin number of the signal that indicates the valid signal from start to finish.
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PIN_TAD: Pin number of the signal that indicates the input/output direction of the target signal (BSY,IO,CD,MSG,REG).
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PIN_IND: Pin number of the signal indicating the input/output direction of the initiator signal (SEL, ATN, RST, ACK).
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PIN_DTD: Pin number of the signal that indicates the input/output direction of the data signal (DT0...DT7,DP).
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・Control signal output logic
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0V:FALSE Specify with 3.3V:TRUE.
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ACT_ON: PIN_ACT signal logic.
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ENB_ON: Logic of PIN_ENB signal.
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TAD_IN:PIN_TAD This is the logic in the input direction.
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IND_IN:PIN_ENB Logic in the input direction.
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DTD_IN:PIN_ENB Logic in the input direction.
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・ SCSI signal pin assignment
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PIN_DT0 to PIN_SEL: Each is the pin number of the SCSI signal.
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□ How to compile
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・Executable files (rascsi, rasctl)
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Fix gpiobus.h
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make clean
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make
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[EOF]
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