MAX31855(9)

NAME
max31855 - Support for the MAX31855 Thermocouple-to-Digital converter using bitbanged spi

SYNOPSIS

loadrt max31855 [count=N|names=name1[,name2...]] [personality=P1[,P2...]]

DESCRIPTION

The component requires at least 3 pins to bitbang spi protocol, for example:

    loadrt max31855 personality=1
    setp hm2_6i25.0.gpio.023.is_output true
    setp hm2_6i25.0.gpio.024.is_output true
    net spi.clk.in    hm2_6i25.0.gpio.023.out     max31855.0.clk.out
    net spi.cs.in     hm2_6i25.0.gpio.024.out     max31855.0.cs.out
    net spi.data0.in  hm2_6i25.0.gpio.033.in_not  max31855.0.data.0.in
    addf max31855.0.bitbang-spi servo-thread

The MAX31855 supports a range of -270C to 1800C, however linearization data is only available for the -200C to 1350C range, beyond which raw temperature is returned.

Temperature pins are provided for readings in Celsius, Fahrenheit and Kelvin, temperature values are not updated while a fault condition is present.

The personality parameter is used to indicate the number of sensors. Multiple sensors share the clk and cs pins, but connect to discrete data input pins. A maximum of 15 sensors are supported.

FUNCTIONS

max31855.N.bitbang-spi (requires a floating-point thread)

PINS

max31855.N.data.M.in bit in (M=0..( personality & 0xf ))
    Pin(s) connected to data out.

max31855.N.cs.out bit out
    Pin connected to cs, pulled low to shift data, pulled high for data refresh.

max31855.N.clk.out bit out
    Pin connected to clk.

max31855.N.temp-celsius.M float out (M=0..( personality & 0xf ))
    Temperature output values in Celsius.

max31855.N.temp-fahrenheit.M float out (M=0..( personality & 0xf ))
    Temperature in Fahrenheit.

max31855.N.temp-kelvin.M float out (M=0..( personality & 0xf ))
    Temperature in Kelvin.

max31855.N.fault.M bit out (M=0..( personality & 0xf ))
    Fault condition detected.

max31855.N.fault-flags.M u32 out (M=0..( personality & 0xf ))
    Fault flags: 0x1 = open sensor, 0x2 short to gnd, 0x3 short to vcc.

AUTHOR

Joseph Calderon

LICENSE

GPL