diff --git a/src/include/gpio.h b/src/include/gpio.h
index ea03a23..4627e44 100644
--- a/src/include/gpio.h
+++ b/src/include/gpio.h
@@ -29,6 +29,7 @@
 void gpio_input_pullup(gpio_t gpio);
 void gpio_input(gpio_t gpio);
 void gpio_output(gpio_t gpio, int value);
+int _gpio_base3_value(gpio_t gpio[], int num_gpio, int binary_first);
 
 /*
  * Read the value presented by the set of GPIOs, when each pin is interpreted
@@ -48,6 +49,39 @@
  * gpio[]: pin positions to read. gpio[0] is less significant than gpio[1].
  * num_gpio: number of pins to read.
  */
-int gpio_base3_value(gpio_t gpio[], int num_gpio);
+static inline int gpio_base3_value(gpio_t gpio[], int num_gpio)
+{
+	return _gpio_base3_value(gpio, num_gpio, 0);
+}
+
+/*
+ * Read the value presented by the set of GPIOs, when each pin is interpreted
+ * as a base-3 digit (LOW = 0, HIGH = 1, Z/floating = 2) in a non-standard
+ * ternary number system where the first 2^n natural numbers are represented
+ * as they would be in a binary system (without any Z digits), and the following
+ * 3^n-2^n numbers use the remaining ternary representations in the normal
+ * ternary system order (skipping the values that were already used up).
+ * This is useful for boards which initially used a binary board ID and later
+ * decided to switch to tri-state after some revisions have already been built.
+ * Example: For num_gpio = 2 we get the following representation:
+ *
+ *   Number      X1     X0
+ *     0          0      0
+ *     1          0      1
+ *     2          1      0
+ *     3          1      1	// Start counting ternaries back at 0 after this
+ *     4          0      2	// Skipping 00 and 01 which are already used up
+ *     5          1      2	// Skipping 10 and 11 which are already used up
+ *     6          2      0
+ *     7          2      1
+ *     8          2      2
+ *
+ * gpio[]: pin positions to read. gpio[0] is less significant than gpio[1].
+ * num_gpio: number of pins to read.
+ */
+static inline int gpio_binary_first_base3_value(gpio_t gpio[], int num_gpio)
+{
+	return _gpio_base3_value(gpio, num_gpio, 1);
+}
 
 #endif /* __SRC_INCLUDE_GPIO_H__ */