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USB board

5 Mar 2019 Kazuyuki Takeda

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This is a 40x40 mm board equipped with FT2232, a dual-line USB driver by FTDI inc. This enables apparent simultaneous two-channel data communication between the OPENCORE NMR spectrometer and the console software installed on a personal computer through a single USB cable. In the current architecture of the OPENCORE NMR, the one channel (channel A) is used in the UART 232 mode for sending/receiving the commands/responses to/from the PPG interface core module built inside the FPGA chip, the other (channel B) for transferring the NMR signals from the RCVR core module to the personal computer in the 245 FIFO mode.

Before using, the mode of operation must be configured to the EPROM on the board using the MProg software (FTDI).

Also, the D2XX driver, which is available from FTDI, has to be installed.

Board design

EAGLE schematic and board files
Gerber files

Note: The component side mean the top (1st) layer, while the solder side does the bottom layer.

Parts List

Part Value Device Package Description
C1 *27p C 1608  
C2 *27p C 1608  
C3 33nF C 3216  
C4 0.1u C 1608  
C5 0.1u C 1608  
C6 0.1u C 1608  
C7 10u C 3216 (polar) tantalum
CN1   FH12-30S-0.5SH   0.5 mm pitch FPC connector (HIROSE)
FB 30 Ohm @ 100 MHz MPZ1608S300A 1608 Ferrite bead (TDK)
R1 27 R 1608  
R2 27 R 1608  
R3 1.5k R 1608  
R4 470 R 1608  
R5 2.2k R 1608  
R6 10k R 1608  
U1   FT2232D   Dual USB UART/FIFO I.C. (FTDI)
U2   67068-704J   USB connector (MOLEX)
U3   **AT93C46-10TU-2.7 Thin Shrink Small Outline Package (TSSOP) Serial EPROM (ATMEL)
U4   LM2937IMP-3.3 SOT-223 Voltage regulator
Y1 6 MHz HC49/4H SMX   6 MHz crystal

*Note: The proper value for C1 and C2 depends on the crystal oscillator. Check the datasheet of the 6 MHz crystal that you use.

**Note: End of production. There should be alternatives. According to the datasheet of FT2232D, EEPROMs with a 16-bit wide configuration are required. And the EEPROM must be operational at a 1 MHz clock rate with a supply voltage between 4.35V and 5.25V.

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