1 files changed, 41 insertions, 0 deletions
diff --git a/main/pbdrv.h b/main/pbdrv.h
new file mode 100644
index 0000000..d0d70c2
--- /dev/null
+++ b/main/pbdrv.h
@@ -0,0 +1,41 @@
+#pragma once
+
+#include "pb-types.h"
+
+/**
+ * This is the RP2040 puzzle bus driver. This file is no longer inside
+ * lib/pbdrv/drv/rp2040 as it is tightly coupled to both the pico-sdk and
+ * freertos functions. I have tried to get FreeRTOS to play nicely with the
+ * CMake subproject layout, but the pico-sdk and the rp2040 port of freertos
+ * both rely on CMake's import() functionality, which makes using FreeRTOS in a
+ * libary context extremely messy.
+ *
+ * The workaround implemented in this driver was already kind of messy, and a
+ * different microcontroller should be used for the main controller instead.
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+//! puzzle bus driver setup
+void pbdrv_setup();
+
+/**
+ * While the RP2040's datasheet claims it supports multi-master configurations
+ * by implementing bus arbitration, it does not natively support a mode where
+ * it is configured as a (multi-)master with a slave address, such that it can
+ * be addressed by other multi-masters. This function includes a hacky
+ * workaround that teporarily sets the RP2040 to I2C master mode to send a
+ * message, and then restores it back to slave mode.
+ *
+ * This approach results in some received frames being (partially) dropped in
+ * the time period between the invocation of this function and the bus becoming
+ * idle (and the message is sent).
+ */
+void pbdrv_i2c_send(i2c_addr_t addr, const uint8_t * buf, size_t sz);
+
+#ifdef __cplusplus
+}
+#endif
+