Colibri Pt100 is an I/O module with one Pt100 temperature sensor inputs. Either 3-wire or 4-wire Pt100 can be used. It is configured with solder bridges on the front panel. These can either be ordered for 3- or 4-wire, or order "none" to do defer that distinction until later.

MAX31865 is the resistor Whetstone bridge A/D converter. It uses SPI instead of I2C.

Analog Devices description of the device

   The MAX31865 is an easy-to-use resistance-to-digital
   converter optimized for platinum resistance temperature
   detectors (RTDs). An external resistor sets the sensitivity
   for the RTD being used and a precision delta-sigma ADC
   converts the ratio of the RTD resistance to the reference
   resistance into digital form. The MAX31865’s inputs are
   protected against overvoltage faults as large as ±45V.
   Programmable detection of RTD and cable open and
   short conditions is included.

A 390Ω (0.1% tolerance) is used as the reference sensor, which allows for a reasonably large measurement range, without sacrificing A/D accuracy.

I2C Addresses

 M24M01    = 0x50-0x51

SPI info

See Colibri 3a for information on how to activate SPI on the carrier board.

Activate (low) CS1 for communication with input 1.
Activate (low) CS0 for communication with input 2.

EEPROM factory layout

See the Colibri EEPROM Layout page for the full picture.

Calibration data in EEPROM

Address	Length	Description
0x0080	4	k-factor for Input1
0x0084	4	m-offset for Input1
0x0088	4	k-factor for Input2
0x008c	4	m-offset for Input2

Test Report

Address	Length	Description
0x0100	4	Year * 12 + month
0x0104	4	Date * 24 + hour
0x0108	8	Reserved for future use.
0x0110	4	EEPROM write/read/erase test. 32 cycles. Each cycle is represented in one bit. 0=Success, 1=Fail.
0x0114	4	Calibration parameters written to EEPROM. 0xffff=fail, 0x0=success
0x0118	4	zeptoforth program written to EEPROM. 0xffff=fail, Bytes written otherwise.
0x011c	4	WebAssembly program written to EEPROM. 0xffff=fail, Bytes written otherwise.
0x0120	32	Reserved for future use.
0x0140	4	Apply 82Ω on Input1, check for within 5%, write raw A/D value to this position, or 0xFFFF if fails.
0x0144	4	Apply 100Ω on Input1, check for within 5%, write raw A/D value to this position, or 0xFFFF if fails.
0x0148	4	Apply 130Ω on Input1, check for within 5%, write raw A/D value to this position, or 0xFFFF if fails.
0x014c	4	Reserved for future use.
0x0150	4	Apply 82Ω on Input2, check for within 5%, write raw A/D value to this position, or 0xFFFF if fails.
0x0154	4	Apply 100Ω on Input2, check for within 5%, write raw A/D value to this position, or 0xFFFF if fails.
0x0158	4	Apply 130Ω on Input2, check for within 5%, write raw A/D value to this position, or 0xFFFF if fails.
0x015c	4	Reserved for future use.