src/adafruit_blinka/microcontroller/mcp2221/mcp2221.py

   1 import time
   2 import hid
   3
   4 # from the C driver
   5 # http://ww1.microchip.com/downloads/en/DeviceDoc/mcp2221_0_1.tar.gz
   6 # others (???) determined during driver developement
   7 # pylint: disable=bad-whitespace
   8 RESP_ERR_NOERR              = 0x00
   9 RESP_ADDR_NACK              = 0x25
  10 RESP_READ_ERR               = 0x7F
  11 RESP_READ_COMPL             = 0x55
  12 RESP_READ_PARTIAL           = 0x54 # ???
  13 RESP_I2C_IDLE               = 0x00
  14 RESP_I2C_START_TOUT         = 0x12
  15 RESP_I2C_RSTART_TOUT        = 0x17
  16 RESP_I2C_WRADDRL_TOUT       = 0x23
  17 RESP_I2C_WRADDRL_WSEND      = 0x21
  18 RESP_I2C_WRADDRL_NACK       = 0x25
  19 RESP_I2C_WRDATA_TOUT        = 0x44
  20 RESP_I2C_RDDATA_TOUT        = 0x52
  21 RESP_I2C_STOP_TOUT          = 0x62
  22
  23 RESP_I2C_MOREDATA           = 0x43 # ???
  24 RESP_I2C_PARTIALDATA        = 0x41 # ???
  25 RESP_I2C_WRITINGNOSTOP      = 0x45 # ???
  26
  27 MCP2221_RETRY_MAX           = 50
  28 MCP2221_MAX_I2C_DATA_LEN    = 60
  29 MASK_ADDR_NACK              = 0x40
  30 # pylint: enable=bad-whitespace
  31
  32 class MCP2221:
  33
  34     VID = 0x04D8
  35     PID = 0x00DD
  36
  37     GP_GPIO = 0b000
  38     GP_DEDICATED = 0b001
  39     GP_ALT0 = 0b010
  40     GP_ALT1 = 0b011
  41     GP_ALT2 = 0b100
  42
  43     def __init__(self):
  44         self._hid = hid.device()
  45         self._hid.open(MCP2221.VID, MCP2221.PID)
  46         self._reset()
  47         time.sleep(0.25)
  48
  49     def _hid_xfer(self, report, response=True):
  50         # first byte is report ID, which =0 for MCP2221
  51         # remaing bytes = 64 byte report data
  52         # https://github.com/libusb/hidapi/blob/083223e77952e1ef57e6b77796536a3359c1b2a3/hidapi/hidapi.h#L185
  53         self._hid.write(b'\0' + report + b'\0'*(64-len(report)))
  54         if response:
  55             # return is 64 byte response report
  56             return self._hid.read(64)
  57
  58     #----------------------------------------------------------------
  59     # MISC
  60     #----------------------------------------------------------------
  61     def gp_get_mode(self, pin):
  62         return self._hid_xfer(b'\x61')[22+pin] & 0x07
  63
  64     def gp_set_mode(self, pin, mode):
  65         # get current settings
  66         current = self._hid_xfer(b'\x61')
  67         # empty report, this is safe since 0's = no change
  68         report = bytearray(b'\x60'+b'\x00'*63)
  69         # set the alter GP flag byte
  70         report[7] = 0xFF
  71         # each pin can be set individually
  72         # but all 4 get set at once, so we need to
  73         # transpose current settings
  74         report[8]  = current[22]  # GP0
  75         report[9]  = current[23]  # GP1
  76         report[10] = current[24]  # GP2
  77         report[11] = current[25]  # GP3
  78         # then change only the one
  79         report[8+pin] = mode & 0x07
  80         # and make it so
  81         self._hid_xfer(report)
  82
  83     def _pretty_report(self, report):
  84         print("     0  1  2  3  4  5  6  7  8  9")
  85         index = 0
  86         for row in range(7):
  87             print("{} : ".format(row), end='')
  88             for _ in range(10):
  89                 print("{:02x} ".format(report[index]), end='')
  90                 index += 1
  91                 if index > 63:
  92                     break
  93             print()
  94
  95     def _status_dump(self):
  96         self._pretty_report(self._hid_xfer(b'\x10'))
  97
  98     def _sram_dump(self):
  99         self._pretty_report(self._hid_xfer(b'\x61'))
 100
 101     def _reset(self):
 102         self._hid_xfer(b'\x70\xAB\xCD\xEF', response=False)
 103         start = time.monotonic()
 104         while time.monotonic() - start < 5:
 105             try:
 106                 self._hid.open(MCP2221.VID, MCP2221.PID)
 107             except OSError:
 108                 # try again
 109                 time.sleep(0.1)
 110                 continue
 111             return
 112         raise OSError("open failed")
 113
 114     #----------------------------------------------------------------
 115     # GPIO
 116     #----------------------------------------------------------------
 117     def gpio_set_direction(self, pin, mode):
 118         report = bytearray(b'\x50'+b'\x00'*63)  # empty set GPIO report
 119         offset = 4 * (pin + 1)
 120         report[offset] = 0x01                   # set pin direction
 121         report[offset+1] = mode                 # to this
 122         self._hid_xfer(report)
 123
 124     def gpio_set_pin(self, pin, value):
 125         report = bytearray(b'\x50'+b'\x00'*63)  # empty set GPIO report
 126         offset = 2 + 4 * pin
 127         report[offset] = 0x01                   # set pin value
 128         report[offset+1] = value                # to this
 129         self._hid_xfer(report)
 130
 131     def gpio_get_pin(self, pin):
 132         resp = self._hid_xfer(b'\x51')
 133         offset = 2 + 2 * pin
 134         if resp[offset] == 0xEE:
 135             raise RuntimeError("Pin is not set for GPIO operation.")
 136         else:
 137             return resp[offset]
 138
 139     #----------------------------------------------------------------
 140     # I2C
 141     #----------------------------------------------------------------
 142     def _i2c_status(self):
 143         resp = self._hid_xfer(b'\x10')
 144         if resp[1] != 0:
 145             raise RuntimeError("Couldn't get I2C status")
 146         return resp
 147
 148     def _i2c_state(self):
 149         return self._i2c_status()[8]
 150
 151     def _i2c_cancel(self):
 152         resp = self._hid_xfer(b'\x10\x00\x10')
 153         if resp[1] != 0x00:
 154             raise RuntimeError("Couldn't cancel I2C")
 155         if resp[2] == 0x10:
 156             # bus release will need "a few hundred microseconds"
 157             time.sleep(0.001)
 158
 159     def _i2c_write(self, cmd, address, buffer, start=0, end=None):
 160         if self._i2c_state() != 0x00:
 161             self._i2c_cancel()
 162
 163         end = end if end else len(buffer)
 164         length = end - start
 165         retries = 0
 166
 167         while (end - start) > 0:
 168             chunk = min(end - start, MCP2221_MAX_I2C_DATA_LEN)
 169             # write out current chunk
 170             resp = self._hid_xfer(bytes([cmd,
 171                                          length & 0xFF,
 172                                          (length >> 8) & 0xFF,
 173                                          address << 1]) +
 174                                          buffer[start:(start+chunk)])
 175             # check for success
 176             if resp[1] != 0x00:
 177                 if resp[2] in (RESP_I2C_START_TOUT,
 178                                RESP_I2C_WRADDRL_TOUT,
 179                                RESP_I2C_WRADDRL_NACK,
 180                                RESP_I2C_WRDATA_TOUT,
 181                                RESP_I2C_STOP_TOUT):
 182                     raise RuntimeError("Unrecoverable I2C state failure")
 183                 retries += 1
 184                 if retries >= MCP2221_RETRY_MAX:
 185                     raise RuntimeError("I2C write error, max retries reached.")
 186                 time.sleep(0.001)
 187                 continue # try again
 188             # yay chunk sent!
 189             while self._i2c_state() == RESP_I2C_PARTIALDATA:
 190                 time.sleep(0.001)
 191             start += chunk
 192             retries = 0
 193
 194         # check status in another loop
 195         for _ in range(MCP2221_RETRY_MAX):
 196             status = self._i2c_status()
 197             if status[20] & MASK_ADDR_NACK:
 198                 raise RuntimeError("I2C slave address was NACK'd")
 199             usb_cmd_status = status[8]
 200             if usb_cmd_status == 0:
 201                 break
 202             if usb_cmd_status == RESP_I2C_WRITINGNOSTOP and cmd == 0x94:
 203                 break   # this is OK too!
 204             if usb_cmd_status in (RESP_I2C_START_TOUT,
 205                                   RESP_I2C_WRADDRL_TOUT,
 206                                   RESP_I2C_WRADDRL_NACK,
 207                                   RESP_I2C_WRDATA_TOUT,
 208                                   RESP_I2C_STOP_TOUT):
 209                 raise RuntimeError("Unrecoverable I2C state failure")
 210             time.sleep(0.001)
 211         else:
 212             raise RuntimeError("I2C write error: max retries reached.")
 213         # whew success!
 214
 215     def _i2c_read(self, cmd, address, buffer, start=0, end=None):
 216         if self._i2c_state() not in (RESP_I2C_WRITINGNOSTOP, 0):
 217             self._i2c_cancel()
 218
 219         end = end if end else len(buffer)
 220         length = end - start
 221
 222         # tell it we want to read
 223         resp = self._hid_xfer(bytes([cmd,
 224                                      length & 0xFF,
 225                                      (length >> 8) & 0xFF,
 226                                      (address << 1) | 0x01]))
 227
 228         # check for success
 229         if resp[1] != 0x00:
 230             raise RuntimeError("Unrecoverable I2C read failure")
 231
 232         # and now the read part
 233         while (end - start) > 0:
 234             for retry in range(MCP2221_RETRY_MAX):
 235                 # the actual read
 236                 resp = self._hid_xfer(b'\x40')
 237                 # check for success
 238                 if resp[1] == RESP_I2C_PARTIALDATA:
 239                     time.sleep(0.001)
 240                     continue
 241                 if resp[1] != 0x00:
 242                     raise RuntimeError("Unrecoverable I2C read failure")
 243                 if resp[2] == RESP_ADDR_NACK:
 244                     raise RuntimeError("I2C NACK")
 245                 if resp[3] == 0x00 and resp[2] == 0x00:
 246                     break
 247                 if resp[3] == RESP_READ_ERR:
 248                     time.sleep(0.001)
 249                     continue
 250                 if resp[2] in (RESP_READ_COMPL, RESP_READ_PARTIAL):
 251                     break
 252
 253             # move data into buffer
 254             chunk = min(end - start, 60)
 255             for i, k in enumerate(range(start, start+chunk)):
 256                 buffer[k] = resp[4 + i]
 257             start += chunk
 258
 259     def i2c_configure(self, baudrate=100000):
 260         self._hid_xfer(bytes([0x10,  # set parameters
 261                               0x00,  # don't care
 262                               0x00,  # no effect
 263                               0x20,  # next byte is clock divider
 264                               12000000 // baudrate - 3]))
 265
 266     def i2c_writeto(self, address, buffer, *, start=0, end=None):
 267         self._i2c_write(0x90, address, buffer, start, end)
 268
 269     def i2c_readfrom_into(self, address, buffer, *, start=0, end=None):
 270         self._i2c_read(0x91, address, buffer, start, end)
 271
 272     def i2c_writeto_then_readfrom(self, address, out_buffer, in_buffer, *,
 273                                   out_start=0, out_end=None,
 274                                   in_start=0, in_end=None):
 275         self._i2c_write(0x94, address, out_buffer, out_start, out_end)
 276         self._i2c_read(0x93, address, in_buffer, in_start, in_end)
 277
 278     def i2c_scan(self, *, start=0, end=0x79):
 279         found = []
 280         for addr in range(start, end+1):
 281             # try a write
 282             try:
 283                 self.i2c_writeto(addr, b'\x00')
 284             except RuntimeError: # no reply!
 285                 continue
 286             # store if success
 287             found.append(addr)
 288         return found
 289
 290     #----------------------------------------------------------------
 291     # ADC
 292     #----------------------------------------------------------------
 293     def adc_configure(self, vref=0):
 294         report = bytearray(b'\x60'+b'\x00'*63)
 295         report[5] = 1 << 7 | (vref & 0b111)
 296         self._hid_xfer(report)
 297
 298     def adc_read(self, pin):
 299         resp = self._hid_xfer(b'\x10')
 300         return resp[49 + 2 * pin] << 8 | resp[48 + 2 * pin]
 301
 302     #----------------------------------------------------------------
 303     # DAC
 304     #----------------------------------------------------------------
 305     def dac_configure(self, vref=0):
 306         report = bytearray(b'\x60'+b'\x00'*63)
 307         report[3] = 1 << 7 | (vref & 0b111)
 308         self._hid_xfer(report)
 309
 310     def dac_write(self, pin, value):
 311         report = bytearray(b'\x60'+b'\x00'*63)
 312         report[4] = 1 << 7 | (value & 0b11111)
 313         self._hid_xfer(report)
 314
 315 mcp2221 = MCP2221()