diff --git a/config.py b/config.py
index 29b9420..293aed7 100644
--- a/config.py
+++ b/config.py
@@ -41,6 +41,7 @@ thermocouple_type = MAX31856.MAX31856_S_TYPE
 gpio_sensor_cs = 27
 gpio_sensor_clock = 22
 gpio_sensor_data = 17
+gpio_sensor_di = 10 # only used with max31856
 
 ### duty cycle of the entire system in seconds. Every N seconds a decision
 ### is made about switching the relay[s] on & off and for how long.
diff --git a/lib/oven.py b/lib/oven.py
index 17ea994..4a1f5b0 100644
--- a/lib/oven.py
+++ b/lib/oven.py
@@ -107,7 +107,8 @@ class TempSensorReal(TempSensor):
             from max31856 import MAX31856
             software_spi = { 'cs': config.gpio_sensor_cs,
                              'clk': config.gpio_sensor_clock,
-                             'do': config.gpio_sensor_data }
+                             'do': config.gpio_sensor_data,
+                             'di': config.gpio_sensor_di }
             self.thermocouple = MAX31856(tc_type=config.thermocouple_type,
                                          software_spi = sofware_spi,
                                          units = config.temp_scale