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--- rnd:projects:tnt [2024-03-10 04:39] – asdf
+++ rnd:projects:tnt [2024-06-02 00:56] (current) – [Prototyping] added CircuitPython code asdf
@@ Line 65: / Line 65: @@
 The LBO pin **cannot** be directly connected to the Teensy! It is pulled high to Vin(([[https://learn.adafruit.com/adafruit-powerboost-500-plus-charger/pinouts]]. It's unclear from the page whether that's always the battery voltage or if it's pulled to the USB voltage when charging. We shall assume the latter as a worst case.)), so it must be level shifted. Unfortunately, a simple voltage divider solution((https://electronics.stackexchange.com/a/231619)) will not suffice. This pin isn't pulled to ground until the battery voltage reaches 3.2 V, but the divider's output will drop below the microcontroller's high voltage threshold when the battery is just below 3.5 V((The threshold is 2.3 V for a 3.3 V supply, and $2.3/0.667\approx 3.46$.)). Given that the battery's dead voltage is 3.0 V (and its nominal voltage is 3.7 V), this is not an ideal transition point. A proper level shifter will be required.
-{{tag>electronics networking teensy}}
+===== Prototyping =====
+Initial development began on the Teensy but shortly thereafter moved to the [[:Feather]] platform for use in the field, where the project has already more than demonstrated its worth. The core Feather boards are completely interchangeable, regardless of microcontroller; have identical pinouts and on-board Li-Po battery chargers; and are programmed in a dialect of Python (CircuitPython) by default((CircuitPython can also be installed on the Teensy and Raspberry Pi Pico.)). For UI and networking, we added the ethernet and OLED FeatherWings. Unlike the Teensy's QNEthernet library, however, the existing ethernet implementation in CircuitPython does not allow for low-level frame access. We thus needed to compose our own partial driver for the WizNet W5500 PHY chip.
+<code python>
+'''
+'''
+import board
+from digitalio import DigitalInOut, Pull, Direction
+import displayio
+from i2cdisplaybus import I2CDisplayBus
+import math
+import terminalio
+import time
+from adafruit_debouncer import Debouncer
+from adafruit_display_text.label import Label
+from adafruit_displayio_ssd1306 import SSD1306
+CS_PIN = board.D10
+BTNA_PIN = board.D9
+BTNB_PIN = board.D6
+BTNC_PIN = board.D5
+OLED_ADDR = 0x3c
+OLED_HEIGHT = 32
+OLED_WIDTH = 128
+MAC_ADDR = '9876b612d4bc'
+# init oled buttons
+btnApin = DigitalInOut(BTNA_PIN)
+btnApin.pull = Pull.UP
+btnBpin = DigitalInOut(BTNB_PIN) # has built-in pull-up
+btnCpin = DigitalInOut(BTNC_PIN)
+btnCpin.pull = Pull.UP
+btnA = Debouncer(btnApin)
+btnB = Debouncer(btnBpin)
+btnC = Debouncer(btnCpin)
+# display elements
+mac = Label(terminalio.FONT, text='', y=4)
+host = Label(terminalio.FONT, text='', y=15)
+iface = Label(terminalio.FONT, text='', y=26)
+def initdisplay():
+    # init oled
+    displayio.release_displays()
+    i2c = board.I2C()
+    displaybus = I2CDisplayBus(i2c, device_address=OLED_ADDR)
+    display = SSD1306(displaybus, width=OLED_WIDTH, height=OLED_HEIGHT)
+    root = displayio.Group()
+    root.append(mac)
+    root.append(host)
+    root.append(iface)
+    display.root_group = root
+    return display
+#
+class Wiznet5500:
+    def __init__(self, cs):
+        self.spi = board.SPI()
+        self.cs = DigitalInOut(cs)
+        self.cs.direction = Direction.OUTPUT
+        self.cs.value = True
+    def reset(self):
+        self.write(0b00000, 0x0000, bytearray.fromhex('80'))
+        return self.read(0b00000, 0x0000, 1)
+    def select(self):
+        while not self.spi.try_lock():
+            pass
+        self.cs.value = False
+    def deselect(self):
+        self.cs.value = True
+        self.spi.unlock()
+    def read(self, block, address, length):
+        data = []
+        # address
+        data.append((address & 0xff00) >> 8)
+        data.append((address & 0x00ff))
+        # control byte
+        data.append((block & 0x1f)<<3)
+        preamble = bytearray(data)
+        # transfer
+        self.select()
+        result = bytearray(length)
+        self.spi.write(bytearray(data))
+        self.spi.readinto(result)
+        self.deselect()
+        return result
+    def write(self, block, address, buf):
+        # buf should already be a bytearray
+        data = []
+        # address
+        data.append((address & 0xff00) >> 8)
+        data.append((address & 0x00ff))
+        # control byte
+        data.append(((block & 0x1f) << 3) | 0x4)
+        # transfer
+        self.select()
+        self.spi.write(bytearray(data))
+        self.spi.write(buf)
+        self.deselect()
+    def recv(self, length):
+        # get Sn_RX_RD
+        ptr = int(self.read(0b00001, 0x0028, 2).hex(), 16)
+        # read data from RX buffer
+        print(f'recv(): getting {length} bytes from {ptr:#x}')
+        data = self.read(0b00011, ptr, length)
+        # update Sn_RX_RD
+        ptr = (ptr + length) & 0xffff
+        out = bytearray.fromhex(f'{ptr:04x}')
+        self.write(0b00001, 0x0028, out)
+        return data
+    def getFrame(self):
+        # get Sn_RX_RSR
+        length = int(self.read(0b00001, 0x0026, 2).hex(), 16)
+        if length > 0:
+            datalen = int(self.recv(2).hex(), 16)-2
+            # Sn_CR_RECV
+            self.write(0b00001, 0x0001, bytearray.fromhex('40'))
+            frame = self.recv(datalen)
+            # Sn_CR_RECV
+            self.write(0b00001, 0x0001, bytearray.fromhex('40'))
+            return frame
+        else:
+            return None
+def processlldp(frame):
+    mac.text = '{0:2x}:{1:2x}:{2:2x}:{3:2x}:{4:2x}:{5:2x}'.format(
+        frame[6], frame[7], frame[8],
+        frame[9], frame[10], frame[11]
+    )
+    pos = 14
+    while pos < len(frame):
+        t = frame[pos] >> 1
+        pos += 1
+        l = (frame[pos-1] << 9) | frame[pos]
+        pos += 1
+        l &= 0x1ff
+        print(f'{t=}, {l=}')
+        if t == 4:
+            iface.text = frame[pos:pos+l].decode('utf-8')
+        elif t == 5:
+            host.text = frame[pos:pos+l].decode('utf-8')
+        pos += l
+def hexdump(ba):
+    l = len(ba)
+    rows = math.ceil(l / 16)
+    r = l % 16
+    for i in range(rows-1):
+        sl = ba[16*i:16*(i+1)]
+        print(f'{sl[0]:02x} {sl[1]:02x} {sl[2]:02x} {sl[3]:02x} {sl[4]:02x} {sl[5]:02x} {sl[6]:02x} {sl[7]:02x} {sl[8]:02x} {sl[9]:02x} {sl[10]:02x} {sl[11]:02x} {sl[12]:02x} {sl[13]:02x} {sl[14]:02x} {sl[15]:02x}')
+    lastrow = ''
+    sl = ba[16*(rows-1):]
+    for i in range(len(sl)):
+        lastrow += f'{sl[i]:02x} '
+    print(lastrow)
+def checkButtons():
+    btnA.update()
+    btnB.update()
+    btnC.update()
+    a = btnA.fell
+    b = btnB.fell
+    c = btnC.fell
+    return a, b, c
+wiznet = Wiznet5500(CS_PIN)
+def main():
+    wiznet.reset()
+    # set tx/rx buf sizes to 16k
+    wiznet.write(0b00001, 0x001e, bytearray.fromhex('10'))
+    wiznet.write(0b00001, 0x001f, bytearray.fromhex('10'))
+    # set mac address
+    wiznet.write(0b00000, 0x0009, bytearray.fromhex(MAC_ADDR))
+    # open socket 0 in MACRAW
+    wiznet.write(0b00001, 0x0000, bytearray.fromhex('04'))
+    wiznet.write(0b00001, 0x0001, bytearray.fromhex('01'))
+    # verify that S0 is open as expected
+    status = int(wiznet.read(0b00001, 0x0003, 1).hex(), 16)
+    if status != 0x42:
+        mac.text = f'S0 {status=:#x}'
+        # HCF?
+    display = initdisplay()
+    mac.text = 'listening for LLDP...'
+    found = False
+    # main loop
+    while True:
+        a, b, c = checkButtons()
+        if found and a:
+            for line in display.root_group:
+                line.x -= 5
+        if found and b:
+            for line in display.root_group:
+                line.x += 6
+        frame = wiznet.getFrame()
+        if not frame:
+            #print('no frame yet')
+            continue
+        found = True
+        ethertype = frame[12:14].hex()
+        if ethertype.lower() == '88cc':
+            processlldp(frame)
+        time.sleep(0.5)
+if __name__ == '__main__':
+    main()
+</code>
+{{tag>electronics networking teensy feather}}