EKM041 Differential I2C Bus Extender Qwiic
Part.no: 41037932
Transceiver module for exending an I2C bus over longer distances using regular Ethernet cable. Using EKM041, I2C signals that normally only work over short distances, can be extended up to 30m.
The differential I2C tranciever IC PCA9615 will handle all signal conversion from regular open-drain I2C to two differential signals for clock and data with high drive capability. The signals are then converted back using another PCA9615 to be used with all common I2C / Qwiic modules.
The conversion to and from differential signals are handled completely transparent and no modifications to the application code is required.
Two of the conductors in the network cable are used for supplying 3.3V and GND. The remaining par can be used for additional signals or a separate power supply and are broken out on the connections marked DC+/DC-.
Please note that the differential interface is not compatible with regular Ethernet and the cables to and from EKM041 must not be connected to regular networking equipment, such as switches or network adapters.
Functions
- Extend I2C signals via networking cable
- Completely transparent to I2C devices
- Robust communication using shielded cable
Specifications
- Voltage supply: 3.3V (3.0 - 5.5V)
- Maximum cable length: approx. 30m
- I2C bus frequencies: 100kHz, 400kHz, 1MHz
- Dimensions: 36 x 20 x 11.3mm
Connections
Voltage supply
If the Qwiic connector is used, the module will be powered this way with 3.3V and no other wires are required for normal use. If the module is wired using the connections along the side, V+a and GND are used for supplying the module with power. The voltage range for V+a is 2.3 - 5.5V.
V+b is a separate supply for the differential side and can handle voltages from 3V to 5.5V. V+b can be separately supplied with a higher voltage to compensate for long cables with higher resistance.
The solder jumper VDDa+b is normally closed, which will supply both sides of the tranciever using a common source. If V+b is supplied separatey, the solder jumper must be opened.
The solder jumpers RJ45 PWR (GND, VDD) are normally closed and directs the supply voltage coming in via the Qwiic connector (or V+a/V+b) through the network cable to the receiving end.
If the devices on each side of the tranciever are separately supplied with power, the VDD jumper must be opened. GND should always be closed to establish a common ground reference.
The connections marked DC+ and DC- are available for use to transmitt other signals or for a separate voltage supply. DC+ and DC- are wired directly to the green/green-white pair in the network cable.
I2C / Qwiic
The connections for I2C clock and data are available both via the Qwiic connector and as individual holes.
The module has pullup resistors and can be disconnected by opening the I2C PU solder jumper.
If the I2C host and the connecting modules already have pullup resistors present, it's usually required to open the jumper to disconnect the resistors.
Enable
The module also breaks out the enable input from the tranciever IC. The enable pin is normally pulled high to make the IC always on. Pull EN low to completely disconnect the transciever from the I2C bus.
Datasheet
Mechanical dimensions
