Resistor Network for the Motherboard

Hello!

The motherboard has RP1,…, RP16 where I assume resistor networks are put in the connectors. What resistance would the networks be?

Thank you in advance.

Depends on what sensors are in which spot. Typically we populate it with the following:

  • Slot M4 - Thermistor (10k ohm) - 103LF
  • Slot M6 - OD135 (100k ohm) - 105LF
  • Slot M7 OD90 (1M ohm) - 104LF

See below for Zack’s correction

Hope that helps.
Brandon

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Hi Eduarda,

You can check out the wiki for an overview of the motherboard.

Zack

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Slight correction to Brandon’s response if you have the most up to date version of the motherboard and RevD of the vial board:

  • Slot M6 - OD90 (1M ohm) - 105LF
  • Slot M7 - OD135 (100k ohm) - 104LF

Slot M7 is likely unpopulated on your setup.

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Multiple resistors are connected together in a circuit arrangement to form resistor networks, also known as resistor arrays. They primarily serve as a voltage divider, breaking up a circuit’s voltage into smaller amounts.I believe resistor networks are installed in the connectors at RP1,…, and RP16 on the motherboard.

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Just to be clear, there is a single resistor for each channel (vial). The resistor packs do not connect the resistors in series or form a larger network - they are a compact package for multiple resistors that share a single ground pin that can be easily interchanged without the need to solder.

From the eVOLVER NBT paper supplement: “Another customizable control board, the ADC board is designed to plug into the Motherboard and measure the signal from dozens of sensors in the system. The sensors currently integrated in each sleeve are simple and can be measured with basic voltage divider circuits. The sensor and resistor are placed in series, and the voltage across a resistor changes when the measurement from the sensor changes. The board reads this voltage and has two main roles: (1) remove noise from the signal through a low pass filter and (2) multiplex the signal from all 16 channels to one analog input pin on the Arduino. When the signal arrives at the input pin, the Arduino changes the analog signal to a digital signal via its own 12-bit ADC.”

So the sensor (which is located on the Smart Sleeve typically) is connected to 3.3V and then the other end is connected to a single resistor on the resistor pack on the motherboard. The output at this node is connected to the ADC filtering/multiplexing circuit and subsequently the ADC on the SAMD21 arduino microcontroller where the value is read.

I’ll have the wiki updated with this information soon and post a link here.