add echo test (no fix needed)

Author: ladyada

examples/gps_echotest.py

@@ -0,0 +1,66 @@
+# Simple GPS module demonstration.
+# Will print NMEA sentences received from the GPS, great for testing connection
+# Uses the GPS only to send some commands, then reads directly from UART
+import time
+import board
+import busio
+
+import adafruit_gps
+
+
+# Define RX and TX pins for the board's serial port connected to the GPS.
+# These are the defaults you should use for the GPS FeatherWing.
+# For other boards set RX = GPS module TX, and TX = GPS module RX pins.
+#RX = board.RX
+#TX = board.TX
+
+# Create a serial connection for the GPS connection using default speed and
+# a slightly higher timeout (GPS modules typically update once a second).
+uart = busio.UART(TX, RX, baudrate=9600, timeout=3000)
+
+# for a computer, use the pyserial library for uart access
+#import serial
+#uart = serial.Serial("/dev/ttyUSB0", baudrate=9600, timeout=3000)
+
+# Create a GPS module instance.
+gps = adafruit_gps.GPS(uart)
+
+# Initialize the GPS module by changing what data it sends and at what rate.
+# These are NMEA extensions for PMTK_314_SET_NMEA_OUTPUT and
+# PMTK_220_SET_NMEA_UPDATERATE but you can send anything from here to adjust
+# the GPS module behavior:
+#   https://cdn-shop.adafruit.com/datasheets/PMTK_A11.pdf
+
+# Turn on the basic GGA and RMC info (what you typically want)
+gps.send_command(b'PMTK314,0,1,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0')
+# Turn on just minimum info (RMC only, location):
+#gps.send_command(b'PMTK314,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0')
+# Turn off everything:
+#gps.send_command(b'PMTK314,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0')
+# Tuen on everything (not all of it is parsed!)
+#gps.send_command(b'PMTK314,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0')
+
+# Set update rate to once a second (1hz) which is what you typically want.
+gps.send_command(b'PMTK220,1000')
+# Or decrease to once every two seconds by doubling the millisecond value.
+# Be sure to also increase your UART timeout above!
+#gps.send_command(b'PMTK220,2000')
+# You can also speed up the rate, but don't go too fast or else you can lose
+# data during parsing.  This would be twice a second (2hz, 500ms delay):
+#gps.send_command(b'PMTK220,500')
+
+# Main loop runs forever printing data as it comes in
+timestamp = time.monotonic()
+while True:
+    data = uart.read(32)  # read up to 32 bytes
+    # print(data)  # this is a bytearray type
+ 
+    if data is not None:
+        # convert bytearray to string
+        data_string = ''.join([chr(b) for b in data])
+        print(data_string, end="")
+
+    if time.monotonic() - timestamp > 5:
+        # every 5 seconds...
+        gps.send_command(b'PMTK605')  # request firmware version
+        timestamp = time.monotonic()