diff --git a/variants/pimoroni_tiny2040/pins_arduino.h b/variants/pimoroni_tiny2040/pins_arduino.h
index f6c61e39..8615dea8 100644
--- a/variants/pimoroni_tiny2040/pins_arduino.h
+++ b/variants/pimoroni_tiny2040/pins_arduino.h
@@ -1,5 +1,39 @@
 #pragma once
 
-// This is a bare board with no real predefined pins, so use generic
+// This is a bare board with few predefined pins, so based on generic
 
-#include "../generic/pins_arduino.h"
+// Pin definitions taken from:
+//    https://datasheets.raspberrypi.org/pico/pico-datasheet.pdf
+//    https://shop.pimoroni.com/products/tiny-2040
+
+// RGB LED on pins 18-20.  Use the Green LED element on pin 19 as LED_BUILTIN
+#define PIN_LED        (19u)
+
+// Serial
+#define PIN_SERIAL1_TX (0u)
+#define PIN_SERIAL1_RX (1u)
+
+#define PIN_SERIAL2_TX (4u)
+#define PIN_SERIAL2_RX (5u)
+
+// SPI = SPI0 only, on GPI0 0-3 or 4-7 (no SS)
+#define PIN_SPI0_MISO  (4u)
+#define PIN_SPI0_MOSI  (7u)
+#define PIN_SPI0_SCK   (6u)
+// PIN_SPI0_SS not available on any header pin but needs to be defined for ../generic/common.h so use a dummy
+#define PIN_SPI0_SS    (17u)
+
+// SPI1 not available - not enough pins
+
+// Wire = WIRE0 on 0-1 or 4-5, WIRE1 on 2-3 or 6-7
+#define PIN_WIRE0_SDA  (4u)
+#define PIN_WIRE0_SCL  (5u)
+
+#define PIN_WIRE1_SDA  (6u)
+#define PIN_WIRE1_SCL  (7u)
+
+#define SERIAL_HOWMANY (3u)
+#define SPI_HOWMANY    (1u)
+#define WIRE_HOWMANY   (2u)
+
+#include "../generic/common.h"