initial
This commit is contained in:
commit
9310fe6abc
112
benchmark.txt
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112
benchmark.txt
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64K
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bilbo@localhost ~ $ dd if=/dev/random of=random bs=64K count=1
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1+0 records in
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1+0 records out
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65536 bytes (66 kB, 64 KiB) copied, 0.000637442 s, 103 MB/s
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for i in `seq 1 10`; do ./tools/ftdi_transfer write 0xac010000 random |& grep -E 'measured|crc'; done
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remote crc: 2af6d258; local crc 2af6d258
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measured write time : 0.425 seconds
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remote crc: 2af6d258; local crc 2af6d258
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measured write time : 0.425 seconds
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remote crc: 2af6d258; local crc 2af6d258
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measured write time : 0.425 seconds
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remote crc: 2af6d258; local crc 2af6d258
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measured write time : 0.425 seconds
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remote crc: 2af6d258; local crc 2af6d258
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measured write time : 0.425 seconds
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remote crc: 2af6d258; local crc 2af6d258
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measured write time : 0.425 seconds
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remote crc: 2af6d258; local crc 2af6d258
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measured write time : 0.425 seconds
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remote crc: 2af6d258; local crc 2af6d258
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measured write time : 0.426 seconds
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remote crc: 2af6d258; local crc 2af6d258
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measured write time : 0.425 seconds
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remote crc: 2af6d258; local crc 2af6d258
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measured write time : 0.425 seconds
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1MB
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dd if=/dev/random of=random bs=1M count=1
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1+0 records in
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1+0 records out
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1048576 bytes (1.0 MB, 1.0 MiB) copied, 0.00464291 s, 226 MB/s
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for i in `seq 1 10`; do ./tools/ftdi_transfer write 0xac010000 random |& grep -E 'measured|crc'; done
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remote crc: de34b971; local crc de34b971
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measured write time : 6.666 seconds
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remote crc: de34b971; local crc de34b971
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measured write time : 6.666 seconds
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remote crc: de34b971; local crc de34b971
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measured write time : 6.663 seconds
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remote crc: de34b971; local crc de34b971
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measured write time : 6.667 seconds
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remote crc: de34b971; local crc de34b971
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measured write time : 6.667 seconds
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remote crc: de34b971; local crc de34b971
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measured write time : 6.667 seconds
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remote crc: de34b971; local crc de34b971
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measured write time : 6.665 seconds
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remote crc: de34b971; local crc de34b971
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measured write time : 6.667 seconds
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remote crc: de34b971; local crc de34b971
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measured write time : 6.664 seconds
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remote crc: de34b971; local crc de34b971
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measured write time : 6.666 seconds
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8MB:
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dd if=/dev/random of=random bs=8M count=1
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1+0 records in
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1+0 records out
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8388608 bytes (8.4 MB, 8.0 MiB) copied, 0.0240846 s, 348 MB/s
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for i in `seq 1 10`; do ./tools/ftdi_transfer write 0xac010000 random |& grep -E 'measured|crc'; done
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remote crc: 1c92e87c; local crc 1c92e87c
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measured write time : 53.247 seconds
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remote crc: 1c92e87c; local crc 1c92e87c
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measured write time : 53.271 seconds
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remote crc: 1c92e87c; local crc 1c92e87c
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measured write time : 53.245 seconds
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remote crc: 1c92e87c; local crc 1c92e87c
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measured write time : 53.242 seconds
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remote crc: 1c92e87c; local crc 1c92e87c
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measured write time : 53.242 seconds
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remote crc: 1c92e87c; local crc 1c92e87c
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measured write time : 53.251 seconds
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remote crc: 1c92e87c; local crc 1c92e87c
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measured write time : 53.271 seconds
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remote crc: 1c92e87c; local crc 1c92e87c
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measured write time : 53.245 seconds
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remote crc: 1c92e87c; local crc 1c92e87c
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measured write time : 53.242 seconds
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remote crc: 1c92e87c; local crc 1c92e87c
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measured write time : 53.270 seconds
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15MB:
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dd if=/dev/random of=random bs=15M count=1
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1+0 records in
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1+0 records out
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15728640 bytes (16 MB, 15 MiB) copied, 0.0500857 s, 314 MB/s
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for i in `seq 1 10`; do ./tools/ftdi_transfer write 0xac010000 random |& grep -E 'measured|crc'; done
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remote crc: 55797d82; local crc 55797d82
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measured write time : 99.868 seconds
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remote crc: 55797d82; local crc 55797d82
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measured write time : 99.868 seconds
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remote crc: 55797d82; local crc 55797d82
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measured write time : 99.870 seconds
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remote crc: 55797d82; local crc 55797d82
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measured write time : 99.865 seconds
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remote crc: 55797d82; local crc 55797d82
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measured write time : 99.822 seconds
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remote crc: 55797d82; local crc 55797d82
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measured write time : 99.869 seconds
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remote crc: 55797d82; local crc 55797d82
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measured write time : 99.819 seconds
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remote crc: 55797d82; local crc 55797d82
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measured write time : 99.821 seconds
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remote crc: 55797d82; local crc 55797d82
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measured write time : 99.871 seconds
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remote crc: 55797d82; local crc 55797d82
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measured write time : 99.866 seconds
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1
ftdi_transfer_readme.txt
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1
ftdi_transfer_readme.txt
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- windows drivers / d2xx / vcp
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41
prototype-differences.txt
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41
prototype-differences.txt
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This is a pre-production prototype. It does not represent the final product.
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The production version will include (at least) the following changes:
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- PCB schematic: The SH7091 SCIF is able to use the RTS2 and CTS2 signals as
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GPIO. However, if RTS and CTS are routed to ADBUS on the FT232H, it is not
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possible to simultaneously configure ADBUS signals as both UART and GPIO. For
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this reason, a new PCB revision will instead route RTS/CTS to the FT232H
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ACBUS. This will allow simultaneous RX/TX UART on ADBUS and GPIO on ACBUS. The
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intent is to allow for more interesting out-of-band signaling, in addition to
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what is possible with a plain UART.
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- PCB schematic: rearranged all ACBUS connections; LEDs moved from ACBUS8/ACBUS9
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to ACBUS0/ACBUS1; G-RESET moved from ACBUS1 to ACBUS5; SCK moved from ACBUS0
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to ACBUS6.
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- PCB layout: increase the size of the serial connector footprint pads
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- PCB layout: increase clearance between passive components and serial connector footprint
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- PCB layout: complete redraw
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- PCB layout: changed USB connector type from USB Mini-B to USB Type-C
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- PCB layout: replaced FT232HL with FT232HQ due to component shortage
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- Serial connector: shield tin-plating applied at the factory
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- Serial connector: conductive pin tin-plating applied at the factory
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- Serial connector: increase thickness of shield pins
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- Serial connector: slightly redimensioned to reduce grinding required for a
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perfect fit in the female connector
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- Serial connector: holes at the front of the pin guides were removed; this is
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to prevent inconsistent bridging seen in some earlier samples
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Other changes that are under consideration:
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- possible inclusion of a Nylon case/enclosure for the PCB (depending on feedback/demand)
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37
questionnaire.txt
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37
questionnaire.txt
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- Would you pay $50 USD + $8 (US) shipping for this adapter?
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Commentary: The serial connector is the main bottleneck on lowering the price.
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- What is your favorite USB connector:
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- USB Type-B (full-size)
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- USB Mini-B
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- USB Micro-B
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- USB Type-C
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Commentary: I think USB Mini-B has a good balance between connector strength
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and size. USB Type-C might be more popular though.
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- Would you pay $10 for a high-quality plastic case for this serial adapter?
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Commentary: I think the exposed PCB has a nice aesthetic. I am also concerned
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about the clearance between the Dreamcast serial port and the Dreamcast AV
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port. It is deliberate that this serial adapter PCB is nearly as narrow as
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possible.
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- The maximum configurable Dreamcast SCIF speed is 1.5Mbit/s. However, it may be
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possible to achieve faster speeds by overclocking the SCIF via the SCIF
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external clock input. If a 1.5Mbit/s adapter is priced at $50 USD, would you
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pay $100 for an adapter with that can transmit and receive at an overclocked
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2.0Mbit/s?
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Commentary: I think this is a funny idea, but I doubt people want to pay for
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it. It is almost certainly a better idea to make a G2 bus (modem connector)
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peripheral for this instead.
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- Do you think there should be a similarly-priced serial adapter product for
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Sega Saturn?
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Commentary: Sega Saturn is slightly more interesting because there are three
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completely separate serial interfaces on the same connector. This is a perfect
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use-case for the FT4232H quad-channel UART chip.
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90
summary.txt
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90
summary.txt
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Product summary:
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Dreamcast USB-UART adapter, featuring new durable Dreamcast serial connector.
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Does not contain recycled/scavenged components from any Sega-original product.
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Usable as a COM/tty port with generic software (FTDI VCP drivers required on
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Windows; usable with no configuration on Linux). Custom software is also
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provided for more advanced functionality.
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What can you do with it?
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This product is primarily intended for people interested in developing new
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software for Sega Dreamcast.
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For Dreamcast units with boot ROMs that will load software from CD-R (e.g: VA0,
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VA1).
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Example/suggested use-cases include:
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- copy newly-written software from a PC to Dreamcast RAM for rapid compile/test cycles
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- create dumps of Dreamcast texture memory (framebuffer "screenshots", Holly/emulator development, application debugging)
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- SH4 debugging via GDB
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- serial printf debugging
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- interactive text console via a terminal emulator (minicom/picocom/screen/putty)
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Many other data transfer use-cases are possible, including VMU save backups and
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CD-ROM/GD-ROM backups.
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Features:
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- Capable of sustained data transfer at 1.5 Mbit/s, read and write (the
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maximum configurable speed of the Dreamcast SCIF)
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- Dreamcast global reset, user-controllable via USB (reset the Dreamcast
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without pressing the power button)
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- Two LEDs, user-controllable via USB (by default configured as TX/RX activity LEDs)
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Transfer benchmarks:
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Benchmarks are performed using the `ftdi_transfer` open source transfer program
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on Linux.
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- 50 kbyte @ 0.425±0.001 seconds (idealized time: 0.419 seconds)
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- 1 Mbyte @ 6.666±0.002 seconds (idealized time: 6.711 seconds)
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- 8 Mbyte @ 53.253±0.015 seconds (idealized time: 53.687 seconds)
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- 15 Mbyte @ 99.854±0.026 seconds (idealized time: 100.663 seconds)
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The integrity of the bytes transferred in each transfer are checked and
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verified. Each test is repeated and averaged 10 times.
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The results where the benchmarked speed is faster than the idealized time are
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not a mistake. This occurs because FT232H chip is transmitting at 1573770
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bits/sec, which is 0.721% faster than the Dreamcast's 1562500 bit/s. The SH7091
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manual specifies (receive) speeds within 1% of the configured rate are
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acceptable. Because the SH7091 SCIF performs 16x oversampling of the received
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serial data and resynchronizes on every start bit, this effectively means that
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the SCIF is being "overclocked" by 0.721% when the receive line is driven by a
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FT232H.
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The results where the benchmarked speed is slower than the idealized time is
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because the round trip time of an extra USB transaction is included in the
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benchmark measurement. This extra USB transaction is used to retrieve the CRC32
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checksum of the transmitted data, as computed by the Dreamcast. The extra USB
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transaction is also used to positively affirm the serial transfer is complete
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(and not simply queued in the FT232H transmit buffer). This USB transaction
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latency is relatively constant, and becomes insignificant with larger transfers.
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Technical specifications:
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Dreamcast serial connector:
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- Aluminium shield/shroud (SLM 3d-printed)
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- Aluminium conductive pins (laser-cut sheet metal)
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- Plastic pin-housing (SLA 3d-printed)
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USB UART PCB:
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- FTDI FT232H USB UART
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- 93LC56BT 2kbit configuration EEPROM
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- custom 4-layer PCB
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