15 files changed, 151 insertions, 63 deletions
diff --git a/lib/pbdrv/CMakeLists.txt b/lib/pbdrv/CMakeLists.txt
index 998ed4d..903a3b4 100644
--- a/lib/pbdrv/CMakeLists.txt
+++ b/lib/pbdrv/CMakeLists.txt
@@ -23,7 +23,7 @@ add_library(pbdrv STATIC
 	pb-buf.c
 	)
 target_include_directories(pbdrv SYSTEM INTERFACE .)
-target_link_libraries(pbdrv mpack)
+target_link_libraries(pbdrv PRIVATE mpack)
 
 # puzzle bus *module* specific code
 add_library(pbdrv-mod OBJECT
@@ -32,9 +32,9 @@ add_library(pbdrv-mod OBJECT
 	pb-route.c
 	)
 target_include_directories(pbdrv-mod SYSTEM INTERFACE .)
-target_link_libraries(pbdrv-mod pbdrv)
+target_link_libraries(pbdrv-mod PUBLIC pbdrv)
 
 # puzzle bus drivers
 include(drv/arduino/include.cmake)
-# include(drv/rp2040/include.cmake) # please see /main/pbdrv.h
+include(drv/rp2040/include.cmake)
 
diff --git a/lib/pbdrv/drv/arduino/include.cmake b/lib/pbdrv/drv/arduino/include.cmake
index 1e2ff08..5ec1124 100644
--- a/lib/pbdrv/drv/arduino/include.cmake
+++ b/lib/pbdrv/drv/arduino/include.cmake
@@ -3,7 +3,7 @@ if(NOT DEFINED ARDUINO)
 endif()
 
 target_sources(pbdrv-mod PRIVATE "${CMAKE_CURRENT_LIST_DIR}/mod.cpp")
-target_link_arduino_libraries(pbdrv-mod core Wire)
+target_link_arduino_libraries(pbdrv-mod PRIVATE core Wire)
 
 # freertos is used to defer the handling of i2c messages outside the receive
 # interrupt service routine
diff --git a/lib/pbdrv/drv/arduino/index.dox b/lib/pbdrv/drv/arduino/index.dox
index 4c74222..03510dd 100644
--- a/lib/pbdrv/drv/arduino/index.dox
+++ b/lib/pbdrv/drv/arduino/index.dox
@@ -2,18 +2,24 @@
 /**
 \ingroup pb_drv
 \defgroup pb_drv_arduino Arduino
-\brief Arduino (Arduino-CMake-Toolchain) driver
-
-This driver is automatically enabled if the variable \c ARDUINO is defined in
-your CMakeLists.txt (it is by default when using Arduino-CMake-Toolchain).
-
-\note This driver automatically includes the
-\ref pb_ext_freertos "FreeRTOS extension" for deferring calls to \c
-pb_i2c_recv() from the I2C ISR.
+\brief Arduino ATmega (w/ Arduino-CMake-Toolchain) driver
 
 This driver is known to work with the following MCUs:
 - ATmega328P (Arduino Uno)
 - ATmega2560 (Arduino Mega)
 
+\par Usage
+- Link the \c pbdrv-mod library with your main executable
+
+\note This driver is automatically enabled if the variable \c ARDUINO is
+defined in your CMakeLists.txt (it is by default when using
+Arduino-CMake-Toolchain).
+
+\note This driver automatically includes the \ref pb_ext_freertos
+"FreeRTOS extension" for deferring calls to \c pb_i2c_recv() from the I2C ISR.
+
+A complete example for this driver is available in the \ref puzzle/dummy
+folder.
+
 */
 
diff --git a/lib/pbdrv/drv/arduino/mod.cpp b/lib/pbdrv/drv/arduino/mod.cpp
index 2eef8d5..c381077 100644
--- a/lib/pbdrv/drv/arduino/mod.cpp
+++ b/lib/pbdrv/drv/arduino/mod.cpp
@@ -1,7 +1,3 @@
-#ifndef ARDUINO
-#error This driver only works on the Arduino platform!
-#endif
-
 #include <Arduino.h>
 #include <Wire.h>
 #include <avr/delay.h>
@@ -42,8 +38,17 @@ static void pb_setup() {
 	Wire.onReceive(recv_event);
 }
 
-/// \ingroup pb_drv_arduino
+/**
+ * \ingroup pb_drv_arduino
+ * \warning This function includes a hard-coded 10ms delay before sending. This
+ * is to work around a weird issue where the Arduino pulls both SDA and SCL low
+ * while attempting to initiate an I2C transmission. We were able to verify
+ * that the Arduino correctly handles bus arbitration under a test scenario
+ * with 2 Uno's, but ran into issues while integrating the Arduino's with the
+ * RP2040.
+ */
 __weak void pb_i2c_send(i2c_addr_t addr, const uint8_t * buf, size_t sz) {
+	vTaskDelay(10 / portTICK_PERIOD_MS); // prevent bus collisions
 	Wire.beginTransmission((int) addr);
 	Wire.write(buf, sz);
 	Wire.endTransmission(true);
@@ -69,6 +74,10 @@ void loop_task() {
  * \ingroup pb_drv_arduino
  * \brief Application entrypoint
  *
+ * This function overrides the default (weak) implementation of the \c main()
+ * function in the Arduino framework. No additional setup is required to use
+ * this driver.
+ *
  * \note I should really be able to use Arduino's initVariant function for
  * this, but I can't seem to get it to link properly using the CMake setup in
  * this repository. Overriding the main() function seems to work, and the
diff --git a/lib/pbdrv/drv/index.dox b/lib/pbdrv/drv/index.dox
index 1fe09e2..89b9247 100644
--- a/lib/pbdrv/drv/index.dox
+++ b/lib/pbdrv/drv/index.dox
@@ -7,19 +7,6 @@
 Like \ref pb_ext "extensions", drivers provide platform-specific
 implementations for various functions used in \ref pbdrv-mod.
 
-Drivers are automatically included based on your build configuration, and you
-only need to ensure \c pbdrv-mod is linked with your final executable in order
-to use one of the available drivers:
-
-```cmake
-# include pbdrv
-add_subdirectory(lib/pbdrv)
-
-# link pbdrv-mod
-target_link_libraries(main pbdrv-mod)
-
-```
-
 If there is no existing driver for your target, you may implement the following
 in order to use \ref pbdrv-mod:
 
diff --git a/lib/pbdrv/drv/rp2040/include.cmake b/lib/pbdrv/drv/rp2040/include.cmake
new file mode 100644
index 0000000..6d25e96
--- /dev/null
+++ b/lib/pbdrv/drv/rp2040/include.cmake
@@ -0,0 +1,11 @@
+if(NOT PICO_PLATFORM STREQUAL "rp2040")
+	return()
+endif()
+
+target_sources(pbdrv-mod PRIVATE "${CMAKE_CURRENT_LIST_DIR}/mod.c")
+target_link_libraries(pbdrv-mod PRIVATE hardware_i2c_headers pico_i2c_slave_headers)
+target_include_directories(pbdrv-mod INTERFACE "${CMAKE_CURRENT_LIST_DIR}")
+
+# pico-stdlib is compatible with C stdlib
+include("${CMAKE_CURRENT_LIST_DIR}/../../ext/stdlib/include.cmake")
+
diff --git a/lib/pbdrv/drv/rp2040/index.dox b/lib/pbdrv/drv/rp2040/index.dox
new file mode 100644
index 0000000..eb01d15
--- /dev/null
+++ b/lib/pbdrv/drv/rp2040/index.dox
@@ -0,0 +1,31 @@
+// vim:ft=doxygen
+/**
+\ingroup pb_drv
+\defgroup pb_drv_rp2040 RP2040
+\brief Raspberry Pi Pico and Pico W driver
+
+This driver is known to work with the following MCUs:
+- Raspberry Pi Pico W
+
+\note 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.
+
+\note This driver includes a workaround that uses both I2C peripherals on the
+RP2040. To use this driver, make sure you initialize both I2C peripherals, and
+connect their respective SDA and SCL pins to the same I2C bus.
+
+\par Usage
+- Link the \c pbdrv-mod library with your main executable
+- Call the \c pb_setup() function (from \c <pb-mod.h>) during setup
+
+\note This driver is automatically enabled if the variable \c PICO_PLATFORM is
+equal to \c "rp2040" in your CMakeLists.txt (it is by default when using the
+pico-sdk CMake library).
+
+\note This driver automatically includes the \ref pb_ext_stdlib
+"stdlib extension" as the pico-sdk implements the C standard library.
+
+*/
+
diff --git a/lib/pbdrv/drv/rp2040/mod.c b/lib/pbdrv/drv/rp2040/mod.c
new file mode 100644
index 0000000..1535da9
--- /dev/null
+++ b/lib/pbdrv/drv/rp2040/mod.c
@@ -0,0 +1,49 @@
+#include "pb.h"
+
+#include "pb.h"
+#include "pb-types.h"
+#include "pb-mod.h"
+#include "pb-send.h"
+#include "pb-buf.h"
+
+#include <hardware/i2c.h>
+#include <hardware/gpio.h>
+#include <pico/i2c_slave.h>
+
+#define PB_I2C_S i2c0
+#define PB_I2C_M i2c1
+
+#define BUF_SIZE 256
+
+uint8_t i2c_msg_buf[BUF_SIZE];
+size_t i2c_msg_buf_sz = 0;
+
+// This function is called from the I2C ISR
+static void recv_event(i2c_inst_t *i2c, i2c_slave_event_t event) {
+	switch (event) {
+		case I2C_SLAVE_RECEIVE: {
+			if (i2c_msg_buf_sz == BUF_SIZE) return;
+			i2c_msg_buf[i2c_msg_buf_sz++] = i2c_read_byte_raw(PB_I2C_S);
+			break;
+		}
+		case I2C_SLAVE_FINISH: {
+			pb_i2c_recv(i2c_msg_buf, i2c_msg_buf_sz);
+			i2c_msg_buf_sz = 0;
+			break;
+		}
+		default: break;
+	}
+}
+
+void pb_setup() {
+	i2c_init(PB_I2C_S, PB_CLOCK_SPEED_HZ);
+	i2c_init(PB_I2C_M, PB_CLOCK_SPEED_HZ);
+
+	i2c_slave_init(PB_I2C_S, PB_MOD_ADDR, &recv_event);
+}
+
+__weak void pb_i2c_send(i2c_addr_t addr, const uint8_t * buf, size_t sz) {
+	// false to write stop condition to i2c bus
+	i2c_write_timeout_us(PB_I2C_M, addr, buf, sz, false, PB_TIMEOUT_US);
+}
+
diff --git a/lib/pbdrv/drv/rp2040/pb-mod.h b/lib/pbdrv/drv/rp2040/pb-mod.h
new file mode 100644
index 0000000..96edc70
--- /dev/null
+++ b/lib/pbdrv/drv/rp2040/pb-mod.h
@@ -0,0 +1,21 @@
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * \ingroup pb_drv_rp2040
+ * \brief Puzzle bus driver setup
+ *
+ * This function must be called from a setup/init function to initialize the
+ * I2C peripherals used by this driver.
+ */
+void pb_setup();
+
+#ifdef __cplusplus
+}
+#endif
+
+#include "../../pb-mod.h"
+
diff --git a/lib/pbdrv/ext/freertos/include.cmake b/lib/pbdrv/ext/freertos/include.cmake
index e7ab7fd..e205c8f 100644
--- a/lib/pbdrv/ext/freertos/include.cmake
+++ b/lib/pbdrv/ext/freertos/include.cmake
@@ -1,9 +1,7 @@
 target_sources(pbdrv PRIVATE "${CMAKE_CURRENT_LIST_DIR}/pb-mem.c")
-target_link_libraries(pbdrv
+target_link_libraries(pbdrv PUBLIC
 	freertos_kernel
 	freertos_kernel_include
 	freertos_config
 	)
 
-target_sources(pbdrv-mod PRIVATE "${CMAKE_CURRENT_LIST_DIR}/pb-mod.c")
-
diff --git a/lib/pbdrv/ext/freertos/index.dox b/lib/pbdrv/ext/freertos/index.dox
index dfa45ff..7d72918 100644
--- a/lib/pbdrv/ext/freertos/index.dox
+++ b/lib/pbdrv/ext/freertos/index.dox
@@ -2,5 +2,5 @@
 /**
 \ingroup pb_ext
 \defgroup pb_ext_freertos FreeRTOS
-\brief FreeRTOS memory management and scheduler-based delay
+\brief FreeRTOS memory management
 */
diff --git a/lib/pbdrv/ext/freertos/pb-mod.c b/lib/pbdrv/ext/freertos/pb-mod.c
deleted file mode 100644
index 5c0aa36..0000000
--- a/lib/pbdrv/ext/freertos/pb-mod.c
+++ /dev/null
@@ -1,10 +0,0 @@
-#include <FreeRTOS.h>
-#include <task.h>
-
-#include "../../pb-types.h"
-
-/// \ingroup pb_ext_freertos
-__weak void pb_mod_blocking_delay_ms(unsigned long ms) {
-	vTaskDelay(ms / portTICK_PERIOD_MS);
-}
-
diff --git a/lib/pbdrv/index.dox b/lib/pbdrv/index.dox
index eb0fd63..8ddcb6a 100644
--- a/lib/pbdrv/index.dox
+++ b/lib/pbdrv/index.dox
@@ -11,8 +11,9 @@ themselves. For a complete puzzle module driver, please see \ref pbdrv-mod.
 
 If you order to use \ref pbdrv, you need to include this folder in your
 CMakeLists.txt file, include the \ref pb_ext "extension" for your target
-platform, and link the \c pbdrv library with your executable:
+platform, and link the \c pbdrv library with your executable.
 
+\par Example
 ```cmake
 # include pbdrv
 add_subdirectory(lib/pbdrv)
@@ -35,14 +36,10 @@ using an existing \ref pb_drv "driver", or (partially) implementing the driver
 functions.
 
 Like \ref pbdrv, \ref pbdrv-mod can be used by including this folder in your
-CMakeLists.txt file and linking the library with your executable. A notable
-difference with \ref pbdrv-mod is that you do not need to include an extension.
-\ref pb_ext "Extensions" are still used by \ref pbdrv-mod, but they are
-included automatically by the target platform's \ref pb_drv "driver". The
-appropriate \ref pb_drv "driver" to load is also automatically detected.
-
-Example:
+CMakeLists.txt file and linking the library with your executable. Please see
+the \ref pb_drv "drivers" page for target-specific usage instructions.
 
+\par Example
 ```cmake
 # include pbdrv
 add_subdirectory(lib/pbdrv)
diff --git a/lib/pbdrv/pb-mod.h b/lib/pbdrv/pb-mod.h
index 3869e55..91e1d1f 100644
--- a/lib/pbdrv/pb-mod.h
+++ b/lib/pbdrv/pb-mod.h
@@ -24,14 +24,6 @@ extern const char * PB_MOD_NAME;
  */
 extern const i2c_addr_t PB_MOD_ADDR;
 
-/**
- * \brief Platform-specific blocking delay function
- *
- * FIXME: this entire function should be removed (see handover: RP2040 I2C
- * limitations)
- */
-void pb_mod_blocking_delay_ms(unsigned long ms);
-
 /// \}
 
 /**
diff --git a/lib/pbdrv/pb-route.c b/lib/pbdrv/pb-route.c
index f5c32d6..5a7bd67 100644
--- a/lib/pbdrv/pb-route.c
+++ b/lib/pbdrv/pb-route.c
@@ -93,9 +93,6 @@ __weak void pb_route_cmd_magic_req(pb_msg_t * msg) {
 	// // return early if magic doesn't match
 	if (pb_memcmp(cmd->magic, pb_cmd_magic_req, sizeof(pb_cmd_magic_req)) != 0) return;
 
-	// FIXME: this should be removed (see handover: RP2040 I2C limitations)
-	pb_mod_blocking_delay_ms(2000);
-
 	pb_buf_t buf = pb_send_magic_res();
 	pb_send_reply(msg, &buf);
 	pb_buf_free(&buf);