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Electronics -- USB Live Oscilloscope: Main Board

Mainboard Circuit

Download USB-Live-Osci: Mainboard circuit schematic:
PNG image (1042x712 as seen below): mainboard.png (31kb)
High-quality PDF: mainboard.pdf (217kb)
Permission to copy and use this schematic is hereby granted provided credit is given where it is due.

USB-Live-Osci: Mainboard circuit schematic [31kb]

Connectors

The mainboard consists mainly of connectors:

  • The USB-FX2 board gets plugged into: USB_CTL2, USB_RW, USB_CTL1, USB_PB, USB_PA, USB_PD as well as 3V3_5_SUP, 3V3_SUP, GND_SUP.
  • The clock generator is connected at CLK_IO and CLK_SUP.
  • The two input boards (ADCV or digital) get connected to AD_CTL1, AD_DATA1, AD_SUP5V_1, AD_SUP3V3_1 for the first board and the same names with suffix 2 for the second board.
  • JP3 and JP5 can be used for external sampling clock when the clock generator is disabled.

Description

To transfer the sampling data, the 16 digital data lines from the two input boards are fed into the 16bit wide bus of the FX2-USB board (USB_PA,). Each input board can have up to 3 control lines (pins 1,2 and 4 of AD_CTL) which are set from the USB-FX2 board's 8051 controller via lines USB_PA1,3,7 and shift register IC2.

IC1A,B form together an RS-flip-flop which was meant to detect FIFO buffer overflows (i.e. when the USB-FX2 board is not able to transmit data over the USB fast enough). It is connected to the clock generator so that it can take action. However, this feature currently is not used at all and the FIFO stall can probably also be detected by a software interrupt in the FX2.

IC1C,D to the necessary clock inversion because ADCV clock and interface clock need to be inverted compared to the latch clock. (See also the waveform diagrams on the schematic.)


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Last modified: 2006-08-19 14:42:18