32 x 4 (128) channel I2C multiplexor

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.

Features

• 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]