RPI_PICO_PPP: Add lte module.

Author: Gadgetoid

micropython/board/RPI_PICO_PPP/manifest.py

@@ -2,4 +2,6 @@
 
 require("bundle-networking")
 
-include("../manifest_pico.py")
+include("../manifest_pico.py")
+
+freeze("../../modules_py", "lte.py")

micropython/modules_py/lte.py

@@ -0,0 +1,215 @@
+from machine import UART, Pin
+from network import PPP
+from micropython import const
+import time
+
+
+DEFAULT_PIN_RST = 35
+DEFAULT_PIN_NETLIGHT = 34
+DEFAULT_PIN_RX = 33
+DEFAULT_PIN_TX = 32
+DEFAULT_UART_ID = 0
+
+DEFAULT_UART_TIMEOUT = const(1)
+DEFAULT_UART_TIMEOUT_CHAR = const(1)
+DEFAULT_UART_RXBUF = const(1024)
+DEFAULT_UART_STARTUP_BAUD = const(115200)
+DEFAULT_UART_BAUD = const(460800)
+
+
+class CellularError(Exception):
+  def __init__(self, message=None):
+    self.message = "CellularError: " + message
+
+
+class LTE():
+    def __init__(self, apn, uart=None, reset_pin=None, netlight_pin=None, netlight_led=None, skip_reset=False):
+        self._apn = apn
+        self._reset = reset_pin or Pin(DEFAULT_PIN_RST, Pin.OUT)
+        self._uart = uart or UART(
+            DEFAULT_UART_ID,
+            tx=Pin(DEFAULT_PIN_TX, Pin.OUT),
+            rx=Pin(DEFAULT_PIN_RX, Pin.OUT))
+        
+        # Set PPP timeouts and rxbuf
+        self._uart.init(
+            timeout=DEFAULT_UART_TIMEOUT,
+            timeout_char=DEFAULT_UART_TIMEOUT_CHAR,
+            rxbuf=DEFAULT_UART_RXBUF)
+        
+        if not skip_reset:
+            self._reset.value(0)
+            time.sleep(1.0)
+            self._reset.value(1)
+
+        if netlight_led:
+            self._led = netlight_led
+            self._netlight = netlight_pin or Pin(DEFAULT_PIN_NETLIGHT, Pin.IN)
+            self._netlight.irq(self._netlight_irq)
+        
+    def _netlight_irq(self, pin):
+        self._led.value(pin.value())
+
+    def ipconfig(self, *args, **kwargs):
+        if len(args):
+            return self._ppp.ipconfig(*args)
+        else:
+            return self._ppp.ipconfig(**kwargs)
+
+    def iccid(self):
+        try:
+            return self._send_at_command("AT+CICCID", 1)
+        except CellularError:
+           return None
+
+    def status(self):
+        lte_status = self._send_at_command("AT+CEREG?", 1)
+        gsm_status = self._send_at_command("AT+CGREG?", 1)
+        return lte_status, gsm_status
+    
+    def signal_quality(self):
+        try:
+            response = self._send_at_command("AT+CSQ", 1)
+            quality = int(response.split(":")[1].split(",")[0])
+            db = -113 + (2 * quality) # conversion as per AT command set datasheet
+            return db
+        except CellularError:
+            pass
+        return None
+    
+    def stop_ppp(self):
+        self._ppp.disconnect()
+        self._send_at_command(f"AT+IPR={DEFAULT_UART_STARTUP_BAUD}")
+        self._flush_uart()
+
+    def start_ppp(self, baudrate=DEFAULT_UART_BAUD, connect=True):
+        self._wait_ready(poll_time=1.0, timeout=30)
+
+        # Switch to a faster baudrate
+        self._send_at_command(f"AT+IPR={baudrate}")
+        self._flush_uart()
+        self._uart.init(
+            baudrate=baudrate,
+            timeout=DEFAULT_UART_TIMEOUT,
+            timeout_char=DEFAULT_UART_TIMEOUT_CHAR,
+            rxbuf=DEFAULT_UART_RXBUF)
+        self._wait_ready(poll_time=1.0)
+
+        # Connect!
+        if connect:
+            self.connect()
+
+        # This will just always time out!?
+        # try:
+        #    self._send_at_command("ATD*99#", timeout=300)
+        # except CellularError as e:
+        #    print(e)
+
+        # Force PPP to use modem's default settings...
+        #time.sleep(2.0)
+        self._flush_uart()
+        self._uart.write("ATD*99#\r")
+        self._uart.flush()
+        #time.sleep(2.0)
+
+        self._ppp = PPP(self._uart)
+        self._ppp.connect()
+        while self._ppp.status() != 4:
+            time.sleep(1.0)
+
+        return self._ppp.ifconfig()
+
+    def connect(self, timeout=60):
+        print("  - setting up cellular uart")
+        # connect to and flush the uart
+        # consume any unsolicited messages first, we don't need those  
+        self._flush_uart()
+
+        print("  - waiting for cellular module to be ready")
+
+        # wait for the cellular module to respond to AT commands
+        self._wait_ready()   
+
+        self._send_at_command("ATE0") # disable local echo  
+        self._send_at_command(f"AT+CGDCONT=1,\"IP\",\"{self._apn}\"") # set apn and activate pdp context  
+
+        # wait for roaming lte connection to be established
+        giveup = time.time() + timeout
+        status = None
+        while status != "+CEREG: 0,5" and status != "+CEREG: 0,1":
+            status = self._send_at_command("AT+CEREG?", 1)
+            time.sleep(0.25)
+            if time.time() > giveup:
+                raise CellularError("timed out getting network registration")    
+
+        # disable server and client certification validation
+        self._send_at_command("AT+CSSLCFG=\"authmode\",0,0") 
+        self._send_at_command("AT+CSSLCFG=\"enableSNI\",0,1")
+
+        print(f"  - SIM ICCID is {self.iccid()}")
+
+    def _wait_ready(self, poll_time=0.25, timeout=10):
+        giveup = time.time() + timeout
+        while time.time() <= giveup:
+            try:
+                self._send_at_command("AT")
+                return # if __send_at_command doesn't throw an exception then we're good!
+            except CellularError as e:
+                print(e)
+                time.sleep(poll_time)
+
+        raise CellularError("timed out waiting for AT response")  
+
+    def _flush_uart(self):
+        self._uart.flush()
+        time.sleep(0.25)
+        while self._uart.any():
+            self._uart.read(self._uart.any())
+            time.sleep(0.25)
+
+    def _send_at_command(self, command, result_lines=0, timeout=5.0):
+        # consume any unsolicited messages first, we don't need those    
+        self._flush_uart()
+
+        self._uart.write(command + "\r")
+        #print(f"  - tx: {command}")
+        self._uart.flush()
+        status, data = self._read_result(result_lines, timeout=timeout)
+
+        print("  -", command, status, data)
+
+        if status == "TIMEOUT":
+            #print.error("  !", command, status, data)
+            raise CellularError(f"cellular module timed out for command {command}")
+
+        if status not in ["OK", "DOWNLOAD"]:
+            #print("  !", command, status, data)
+            raise CellularError(f"non 'OK' or 'DOWNLOAD' result for command {command}")
+
+        if result_lines == 1:
+            return data[0]
+        if result_lines > 1:
+            return data  
+        return None
+
+    def _read_result(self, result_lines, timeout=1.0):
+        status = None
+        result = []
+        start = time.ticks_ms()
+        timeout *= 1000
+        while len(result) < result_lines or status is None:
+            if (time.ticks_ms() - start) > timeout:
+                return "TIMEOUT", []
+
+            line = self._uart.readline()
+
+            if line:
+                line = line.strip()
+                if line in [b"OK", b"ERROR", b"DOWNLOAD"]:
+                    status = line.decode("ascii")
+                elif line != b"":
+                    result.append(str(line, "ascii"))
+                start = time.ticks_ms()
+
+        return status, result
+