Created cmake file for this as a proper library.

Edited example cmake files to use library rather than manually add the sources.

Removed unused include that needed an extra library to compile.

Fixed a small compile warning when comparing signed to unsigned.

CMakeLists.txt

@@ -0,0 +1,26 @@
+set(lib_name pico_pio_usb)
+add_library(${lib_name} INTERFACE)
+
+set(dir ${CMAKE_CURRENT_LIST_DIR}/src)
+
+pico_generate_pio_header(${lib_name} ${dir}/usb_tx.pio)
+pico_generate_pio_header(${lib_name} ${dir}/usb_rx.pio)
+
+target_sources(${lib_name} INTERFACE
+    ${dir}/pio_usb.c
+    ${dir}/pio_usb_device.c
+    ${dir}/pio_usb_host.c
+    ${dir}/usb_crc.c
+)
+
+target_link_libraries(${lib_name} INTERFACE
+    pico_stdlib
+    pico_multicore
+    hardware_pio
+    hardware_dma
+)
+
+target_include_directories(${lib_name} INTERFACE ${dir})
+
+# enable all warnings
+target_compile_options(${lib_name} INTERFACE -Wall -Wextra)

example/CMakeLists.txt

@@ -5,6 +5,11 @@ project(pio_usb)
 
 pico_sdk_init()
 
+# add pico-pio-usb library for examples
+set(PICO_PIO_USB_DIR "${CMAKE_CURRENT_LIST_DIR}/../")
+# the second argument to add_subdirectory is needed here because this isn't
+# a subdirectory, it's out of tree.
+add_subdirectory(${PICO_PIO_USB_DIR} pico_pio_usb)
 
 add_subdirectory(capture_hid_report)
 add_subdirectory(usb_device)

example/capture_hid_report/CMakeLists.txt

@@ -3,22 +3,13 @@ add_executable(${target_name})
 
 pico_enable_stdio_usb(${target_name} 1) 
 
-set(PICO_PIO_USB_SRC "${CMAKE_CURRENT_LIST_DIR}/../../src")
-
-pico_generate_pio_header(${target_name} ${PICO_PIO_USB_SRC}/usb_tx.pio)
-pico_generate_pio_header(${target_name} ${PICO_PIO_USB_SRC}/usb_rx.pio)
-
 target_sources(${target_name} PRIVATE
  capture_hid_report.c
- ${PICO_PIO_USB_SRC}/pio_usb.c
- ${PICO_PIO_USB_SRC}/pio_usb_device.c
- ${PICO_PIO_USB_SRC}/pio_usb_host.c
- ${PICO_PIO_USB_SRC}/usb_crc.c
  )
+
+# print memory usage, enable all warnings
 target_link_options(${target_name} PRIVATE -Xlinker --print-memory-usage)
 target_compile_options(${target_name} PRIVATE -Wall -Wextra)
-target_include_directories(${target_name} PRIVATE ${PICO_PIO_USB_SRC})
 
-target_link_libraries(${target_name} PRIVATE pico_stdlib pico_multicore hardware_pio hardware_dma)
+target_link_libraries(${target_name} PRIVATE pico_stdlib pico_multicore pico_pio_usb)
 pico_add_extra_outputs(${target_name})
-

example/host_hid_to_device_cdc/CMakeLists.txt

@@ -1,24 +1,21 @@
 set(target_name host_hid_to_device_cdc)
 add_executable(${target_name})
 
-set(PICO_PIO_USB_SRC "${CMAKE_CURRENT_LIST_DIR}/../../src")
-
-pico_generate_pio_header(${target_name} ${PICO_PIO_USB_SRC}/usb_tx.pio)
-pico_generate_pio_header(${target_name} ${PICO_PIO_USB_SRC}/usb_rx.pio)
-
 target_sources(${target_name} PRIVATE
  host_hid_to_device_cdc.c
  usb_descriptors.c
- ${PICO_PIO_USB_SRC}/pio_usb.c
- ${PICO_PIO_USB_SRC}/pio_usb_device.c
- ${PICO_PIO_USB_SRC}/pio_usb_host.c
- ${PICO_PIO_USB_SRC}/usb_crc.c
  )
+
+ # print memory usage, enable all warnings
 target_link_options(${target_name} PRIVATE -Xlinker --print-memory-usage)
 target_compile_options(${target_name} PRIVATE -Wall -Wextra)
-target_include_directories(${target_name} PRIVATE ${PICO_PIO_USB_SRC} ${CMAKE_CURRENT_LIST_DIR})
+
+# use tinyusb implementation
 target_compile_definitions(${target_name} PRIVATE PIO_USB_USE_TINYUSB)
 
-target_link_libraries(${target_name} PRIVATE pico_stdlib pico_multicore hardware_pio hardware_dma tinyusb_device tinyusb_host)
+# needed so tinyusb can find tusb_config.h
+target_include_directories(${target_name} PRIVATE ${CMAKE_CURRENT_LIST_DIR})
+
+target_link_libraries(${target_name} PRIVATE pico_stdlib pico_pio_usb tinyusb_device tinyusb_host)
 pico_add_extra_outputs(${target_name})
 

example/usb_device/CMakeLists.txt

@@ -3,22 +3,14 @@ add_executable(${target_name})
 
 pico_enable_stdio_usb(${target_name} 1) 
 
-set(PICO_PIO_USB_SRC "${CMAKE_CURRENT_LIST_DIR}/../../src")
-
-pico_generate_pio_header(${target_name} ${PICO_PIO_USB_SRC}/usb_tx.pio)
-pico_generate_pio_header(${target_name} ${PICO_PIO_USB_SRC}/usb_rx.pio)
-
 target_sources(${target_name} PRIVATE
   usb_device.c
-  ${PICO_PIO_USB_SRC}/pio_usb.c
-  ${PICO_PIO_USB_SRC}/pio_usb_device.c
-  ${PICO_PIO_USB_SRC}/pio_usb_host.c
-  ${PICO_PIO_USB_SRC}/usb_crc.c
 )
+
+# print memory usage, enable all warnings
 target_link_options(${target_name} PRIVATE -Xlinker --print-memory-usage)
 target_compile_options(${target_name} PRIVATE -Wall -Wextra)
-target_include_directories(${target_name} PRIVATE ${PICO_PIO_USB_SRC})
 
-target_link_libraries(${target_name} PRIVATE pico_stdlib pico_multicore hardware_pio hardware_dma)
+target_link_libraries(${target_name} PRIVATE pico_stdlib pico_multicore pico_pio_usb)
 pico_add_extra_outputs(${target_name})
 

src/pio_usb.c

@@ -14,7 +14,6 @@
 #include "hardware/pio.h"
 #include "hardware/sync.h"
 #include "pico/bootrom.h"
-#include "pico/multicore.h"
 #include "pico/stdlib.h"
 
 #include "pio_usb.h"
@@ -152,6 +151,7 @@ int __no_inline_not_in_flash_func(pio_usb_bus_receive_packet_and_handshake)(
   uint16_t crc_prev = 0xffff;
   uint16_t crc_prev2 = 0xffff;
   uint16_t crc_receive = 0xffff;
+  uint16_t crc_receive_inverse;
   bool crc_match = false;
   int16_t t = 240;
   uint16_t idx = 0;
@@ -177,7 +177,8 @@ int __no_inline_not_in_flash_func(pio_usb_bus_receive_packet_and_handshake)(
           crc = update_usb_crc16(crc, data);
           pp->usb_rx_buffer[idx++] = data;
           crc_receive = (crc_receive >> 8) | (data << 8);
-          crc_match = ((crc_receive ^ 0xffff) == crc_prev2);
+          crc_receive_inverse = crc_receive ^ 0xffff;
+          crc_match = (crc_receive_inverse == crc_prev2);
         }
       }