Add TinyUSB serial library support - #162
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Aug 4, 2026
Several cores offer a "USB Stack: TinyUSB" menu option, and with it selected
Serial is an Adafruit_USBD_CDC rather than the core's own class. The include
ladder still pulled in the core's USB header, which redeclares Serial:
adafruit:samd:adafruit_feather_m0:usbstack=tinyusb
USBAPI.h:189: error: conflicting declaration 'Serial_ Serial'
rp2040:rp2040:rpipico:usbstack=tinyusb
SerialUSB.h:87: error: conflicting declaration 'SerialUSB Serial'
Both measured on HEAD before this commit and passing after. Controls that
must not move, all PASS both ways: gemma_m0, rpipico with the default
stack, teensy40, leonardo, esp32.
twhiston's PR #162 identified this and put a USE_TINYUSB branch first in
the ladder, which is the right shape. It is not merged as sent, for two
reasons found by building it:
- It includes <Adafruit_USBD_CDC.h>. That is the header declaring the
class, but it lives in .../Adafruit_TinyUSB_Arduino/src/arduino, which
the cores add with a raw -I. arduino-cli's library resolver never sees
it, so the TinyUSB library is never linked and every target board dies
at "undefined reference to Adafruit_USBD_CDC::begin". Including
<Adafruit_TinyUSB.h> instead is what makes the resolver pull the
library in -- the same trap 46789e6 hit on nRF52.
- Adafruit's nRF52 core defines -DUSE_TINYUSB unconditionally, so as sent
the new branch shadowed the ARDUINO_NRF52_ADAFRUIT arm that 46789e6
added to make that board link, turning feather52840 from PASS to a link
failure.
Using the resolver-visible header fixes the targeted boards and leaves
nRF52 working, so the nRF52 arm is now redundant but harmless.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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Adds a check to enable TinyUSB support for SlipEncodedSerial.h