32 x 4 (128) channel I2C multiplexor

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Documents: Schematic / Analog switch

Description: The 1498 is a 128 channel I2C (Or analog) multiplexer that is arranged as 32 banks (1 to 32) of 4 channels (A to D) each.  The multiplexer is controlled via a USB serial interface as well as on-board push buttons that can be used to manually select the active bank. 

Note:  No supplementary ESD protection is provided beyond that integrated into the semiconductor devices because this is meant to be used in an electronics laboratory setting where ESD protective protocols are followed.


  • USB powered (USB-B connector) with FTDI FT232RL
  • 1 of 32x4 operation
  • Multiplexing accomplished with MC74LVXT4066 analog switches rated at 25 ohms max
  • I2C signal (Or analog) voltage range on any pin -0.5 to +5.5V
  • 4 signals per connector are switched for I2C:  Power, Ground, SCL and SDA
  • Currently selected bank displayed on backlit LCD
  • Supplied with 1/4" 4-40 standoffs 9 places
  • Conformal coated with silicone

 Manual control

  • SW2  Select bank 01
  • SW3  Increment bank selection (Rolls over from 32 to 01)
  • SW4  Decrement bank selection (Rolls under from 01 to 32)
  • SW6  Pressing while applying power forces device to enter bootloader mode
  • SW1, SW5 are for future functions

Software control

  • Baud rate is 115200,n,8,1
  • Read FW ID where RR is the revision number
  •   Command:   $0000[cr]
  •   Response:  !0000022201RR[nl]
  • Set the mux bank channel where nn is hexadecimal "00" to "1F" for banks 1 to 32
  •   Command:   $0010nn[cr]
  •   Response:  !0010a[nl]
  • Read the current mux bank channel
  •   Command:   $0011[cr]
  •   Response:  !0011nn[nl]


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