A few minor fixes for corner cases

* Always clear the peripheral interrupt so we don't hang when full
* Store the ringbuf in the object so it gets collected when we're alive
* Make UART objects have a finaliser so they are deinit when their
  memory is freed
* Copy bytes into the ringbuf from the FIFO after we read to ensure
  the interrupt is enabled ASAP
* Copy bytes into the ringbuf from the FIFO before measuring our
  rx available because the interrupt is based on a threshold (not
  > 0). For example, a single byte won't trigger an interrupt.

1 files changed, 18 insertions, 0 deletions

diff --git a/tests/manual/busio/uart_echo.py b/tests/manual/busio/uart_echo.py
new file mode 100644
index 000000000..f55d4db9e
--- /dev/null
+++ b/tests/manual/busio/uart_echo.py
@@ -0,0 +1,18 @@
+import busio
+import board
+import time
+
+i = 0
+
+u = busio.UART(tx=board.TX, rx=board.RX)
+
+while True:
+    u.write(str(i).encode("utf-8"))
+    time.sleep(0.1)
+    print(i, u.in_waiting) # should be the number of digits
+    time.sleep(0.1)
+    print(i, u.in_waiting) # should be the number of digits
+    r = u.read(64 + 10)
+    print(i, u.in_waiting) # should be 0
+    print(len(r), r)
+    i += 1