py7seg

27 ''' 28 Abstraction of the 4 digit 7-segment display based on the SAA1064 display driver. 29 If no display is found, all display methods return immediately. The static variable SharedConstants.PATTERN defines a dictionary 30 that maps ASCII characters to display patterns and can be modified by the user program. 31 32 Default: 33 34 The 7 segments have the following binary weights 35 1 36 - 37 32 | |2 38 39 64 40 - 41 16 | |4 42 - 43 8 44 45 The decimal points has weight 128. 46 47 ''' 48 49 DEBUG = False 50 VERSION = "1.00 - April 2016" 51 52 ''' 53 Character to binary value mapping for 4 digit 7 segment display 54 ''' 55 PATTERN = {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`': 32, 62 'a': 119, 'b': 124, 'c': 88, 'd': 94, 'e': 121, 'f': 113, 'g': 61, 'h': 116, 'i': 16, 63 'j': 12, 'k': 112, 'l': 48, 'm': 85, 'n': 84, 'o': 92, 'p': 115, 'q': 103, 'r': 80, 's': 45, 64 't': 120, 'u': 28, 'v': 54, 'w': 106, 'x': 73, 'y': 110, 'z': 27, '{': 0, '|': 48, '}': 0, '~': 65} 65 66 # ----------------------- static methods --------------------- 67 @staticmethod

68 - def debug(msg):

69 if Py7Seg.DEBUG: 70 print "Py7Seg debug->", msg

71 72 @staticmethod

73 - def getVersion():

74 return Py7Seg.VERSION

75 76 @staticmethod

77 - def getDisplayableChars():

78 ''' 79 Returns a string with all displayable characters taken from PATTERN dictionary. 80 @return: The character set that can be displayed 81 ''' 82 s = "<SPACE>" 83 k = 33 84 while k < 127: 85 ch = chr(k) 86 if Py7Seg.PATTERN[ch] != 0: 87 s = s + ch 88 k += 1 89 return s

90 91 @staticmethod

92 - def toHex(intValue):

93 ''' 94 Returns a string with hex digits from given number (>0, any size). 95 @param number: the number to convert (must be positive) 96 @return: string of hex digits (uppercase), e.g. 0xFE 97 ''' 98 return '%02x' % intValue

99 100 @staticmethod

101 - def toBytes(intValue):

102 ''' 103 Returns a list of four byte values [byte#24-#31, byte#16-#23, byte#8-#15, byte#0-#7] of given integer. 104 @param number: an integer 105 @return: list with integers of 4 bytes [MSB,..., LSB] 106 ''' 107 byte0 = intValue & 0xff 108 byte1 = (intValue >> 8) & 0xff 109 byte2 = (intValue >> 16) & 0xff 110 byte3 = (intValue >> 24) & 0xff 111 return [byte3, byte2, byte1, byte0]

112 113 @staticmethod

114 - def toInt(hexValue):

115 ''' 116 Returns an integer from given hex string 117 @param number: a string with the number to convert, e.g. "FE" or "fe" or "0xFE" or "0XFE" 118 @return: integer number 119 ''' 120 return int(hexValue, 16)

121 122 @staticmethod

123 - def delay(timeout):

124 time.sleep(timeout / 1000.0)

125 126 # ----------------------- Constructor ------------------------

127 - def __init__(self, i2c_address = 0x38):

128 ''' 129 Creates a display instance with display set to given i2c address (default: 0x38). 130 The display is NOT cleared. It is set to the lowest brightness level 1 (4 mA). 131 @param i2c_address: the i2c address (default: 0x38) 132 ''' 133 self.i2c_address = i2c_address 134 self._bus = None 135 self._isReady = True 136 self._tickerThread = None 137 self._blinkerThread = None 138 139 try: 140 if GPIO.RPI_REVISION > 1: 141 self._bus = SMBus(1) # For revision 2 Raspberry Pi 142 Py7Seg.debug("I2C at bus 1 detected") 143 else: 144 self._bus = SMBus(0) # For revision 1 Raspberry Pi 145 Py7Seg.debug("I2C at bus 0 detected") 146 except: 147 Py7Seg.debug("Failed to detect I2C bus.") 148 149 if self._isReady: 150 self._startPos = -1 # no text yet 151 self.setBrightness(1)

152 153 # ----------------------- Methods ----------------------

154 - def setBrightness(self, brightness):

155 ''' 156 Sets the brightness of the display. 157 @param luminosity the brightness (0..7, 0: invisible) 158 ''' 159 instruction_byte = 0x00 160 if brightness < 0: 161 brightness = 0 162 if brightness > 7: 163 brightness = 7 164 control_byte = 7 + (brightness << 4) 165 166 # control_byte = 0b00010111 167 # b0 = 1: dynamic mode (autoincrement digits) 168 # b1 = 1: digit 1/3 not blanked, b2 = 1: digit 2/4 not blanked 169 # b4 = 1: 3 mA segment current 170 # write to control register 171 self._bus.write_byte_data(self.i2c_address, instruction_byte, control_byte)

172

173 - def writeData(self, data):

174 ''' 175 Sends 4 data bytes to the display 176 @param data list or tuple of integers whose lower byte are used (higher bytes 177 are ignored). 178 ''' 179 if not self._isReady: 180 return 181 if not (type(data) == list or type(data) == tuple) or len(data) != 4: 182 raise Exception("Error in Py7Seg.writeData():\nWrong parameter type.") 183 for v in data: 184 if not (type(v) == int): 185 raise Exception("Error in Py7Seg.writeData():\nWrong parameter type.") 186 try: 187 cmd = 1 # start with digit 1 188 Py7Seg.debug("bus.write_i2c_block_data(" + str(self.i2c_address) + "," + str(cmd) + "," + str(data) + ")") 189 self._bus.write_i2c_block_data(self.i2c_address, cmd, data) 190 except IOError, err: 191 raise Exception("Py7Seg.writeData(). Can't access device at address 0x%02X" % self.i2c_address)

192

193 - def clear(self):

194 ''' 195 Clears the display (all digits are turned off). 196 ''' 197 Py7Seg.debug("Calling clear()") 198 if not self._isReady: 199 return 200 self._bus.write_i2c_block_data(self.i2c_address, 1, [0, 0, 0, 0])

201

202 - def showText(self, text, pos = 0, dp = [0, 0, 0, 0]):

203 ''' 204 Displays 4 characters of the given text. The text is considered to be prefixed and postfixed by spaces 205 and the 4 character window is selected by the text pointer pos that determines the character displayed at the 206 leftmost digit, e.g. (_: empty): 207 showText("AbCdEF") -> AbCd 208 showText("AbCdEF", 1) -> bCdE 209 showText("AbCdEF", -1) ->_AbC 210 showText("AbCdEF", 4) -> EF__ 211 @param text: the text to display (list, tuple, string or integer) 212 @param pos: the start value of the text pointer (character index positioned a leftmost digit) 213 @param dp: a list with one to four 1 or 0, if the decimal point is shown or not. For compatibility with 214 the 4tronix display, the following mapping is used: 215 The first element in list corresponds to dp at second digit from the right, the second element to dp 216 at third digit from the right, the third element to dp at leftmost digit, the forth element to the dp at 217 rightmost digit. More than 4 elements are ignored 218 @return: True, if successful; False, if the display is not available, 219 text or dp has illegal type or one of the characters can't be displayed 220 ''' 221 Py7Seg.debug("showText(" + str(text) + "," + str(pos) + "," + str(dp) + ")") 222 if not self._isReady: 223 return False 224 if not (type(text) == int or type(text) == list or type(text) == tuple or type(text) == str): 225 return False 226 if not (type(dp) == list or type(dp) == tuple): 227 return False 228 self._startPos = pos 229 self._pos = pos 230 dpList = [0] * 4 231 for i in range(min(4, len(dp))): 232 dpList[i] = dp[i] 233 self._decimalPoint = [0] * 4 234 self._decimalPoint[0] = dpList[2] 235 self._decimalPoint[1] = dpList[1] 236 self._decimalPoint[2] = dpList[0] 237 self._decimalPoint[3] = dpList[3] 238 text = str(text) # convert digits to chars 239 self._text = [' '] * len(text) 240 for i in range(len(text)): 241 try: 242 self._text[i] = Py7Seg.PATTERN[text[i]] 243 except: 244 self._text[i] = 0 # empty 245 data = self._getData(self._pos) 246 self.writeData(data) 247 return True

248

249 - def scrollToLeft(self):

250 ''' 251 Scrolls the current text one step to the left by increasing the text pointer. 252 @return: the number of characters hidden, but remaining to be displayed at the right (>=0); -1, if error 253 ''' 254 if not self._isReady: 255 return -1 256 if self._startPos == -1: # no text yet 257 return -1 258 self._pos += 1 259 data = self._getData(self._pos) 260 self.writeData(data) 261 nb = len(self._text) - self._pos 262 return max(0, nb)

263

264 - def scrollToRight(self):

265 ''' 266 Scrolls the current text one step to the left by decreasing the text pointer. 267 @return: the number of characters hidden, but remaining to be displayed at the left (>=0); -1, if error 268 ''' 269 if not self._isReady: 270 return -1 271 if self._startPos == -1: # no text yet 272 return -1 273 self._pos -= 1 274 pos = self._pos 275 data = self._getData(self._pos) 276 self.writeData(data) 277 return max(0, self._pos)

278

279 - def setToStart(self):

280 ''' 281 Shows the scrollable text at the start position by setting the text pointer to its start value. 282 @return: 0, if successful; -1, if error 283 ''' 284 if not self._isReady: 285 return -1 286 if self._startPos == -1: # no text yet 287 return -1 288 self._pos = self._startPos 289 data = self._getData(self._pos) 290 self.writeData(data) 291 return 0

292

293 - def showTicker(self, text, count = 1, speed = 2, blocking = False):

294 ''' 295 Shows a ticker text that scroll to the left until the last 4 characters are displayed. The method blocks 296 until the ticker thread is successfully started and isTickerAlive() returns True. 297 @param text: the text to display, if short than 4 characters, scrolling is disabled 298 @param count: the number of repetitions (default: 1). For count = 0, infinite duration, 299 may be stopped by calling stopTicker(). 300 @param speed: the speed number of scrolling operations per sec (default: 2) 301 @param blocking: if True, the method blocks until the ticker has finished; otherwise 302 it returns immediately (default: False) 303 ''' 304 if not self._isReady: 305 return 306 self.clear(); 307 if self._tickerThread != None: 308 self.stopTicker() 309 if self._blinkerThread != None: 310 self.stopBlinker() 311 self._tickerThread = TickerThread(self, text, count, speed) 312 if blocking: 313 while self.isTickerAlive(): 314 continue

315

316 - def stopTicker(self):

317 ''' 318 Stops a running ticker. 319 The method blocks until the ticker thread is finished and isTickerAlive() returns False. 320 ''' 321 if not self._isReady: 322 return 323 if self._tickerThread != None: 324 self._tickerThread.stop() 325 self._tickerThread = None

326

327 - def isTickerAlive(self):

328 ''' 329 @return: True, if the ticker is displaying; otherwise False 330 ''' 331 if not self._isReady: 332 return False 333 Py7Seg.delay(1) 334 if self._tickerThread == None: 335 return False 336 return self._tickerThread._isAlive

337

338 - def showBlinker(self, text, dp = [0, 0, 0, 0], count = 3, speed = 1, blocking = False):

339 ''' 340 Shows a ticker text that scroll to the left until the last 4 characters are displayed. The method blocks 341 until the ticker thread is successfully started and isTickerAlive() returns True. 342 @param text: the text to display, if short than 4 characters, scrolling is disabled 343 @param count: the number of repetitions (default: 2). For count = 0, infinite duration, 344 may be stopped by calling stopBlinker(). 345 @param speed: the speed number of blinking operations per sec (default: 1) 346 @param blocking: if True, the method blocks until the blinker has finished; otherwise 347 it returns immediately (default: False) 348 ''' 349 if not self._isReady: 350 return 351 self.clear(); 352 if self._tickerThread != None: 353 self.stopTicker() 354 if self._blinkerThread != None: 355 self.stopBlinker() 356 self._blinkerThread = BlinkerThread(self, text, dp, count, speed) 357 if blocking: 358 while self.isBlinkerAlive(): 359 continue

360

361 - def stopBlinker(self):

362 ''' 363 Stops a running blinker. 364 The method blocks until the blinker thread is finished and isBlinkerAlive() returns False. 365 ''' 366 if not self._isReady: 367 return 368 if self._blinkerThread != None: 369 self._blinkerThread.stop() 370 self._blinkerThread = None

371

372 - def isBlinkerAlive(self):

373 ''' 374 @return: True, if the blinker is displaying; otherwise False 375 ''' 376 if not self._isReady: 377 return False 378 Py7Seg.delay(1) 379 if self._blinkerThread == None: 380 return False 381 return self._blinkerThread._isAlive

382

383 - def showVersion(self):

384 ''' 385 Displays current version. Format X (three horz bars) + n.nn 386 ''' 387 v = "X" + Py7Seg.VERSION.replace(".", "") 388 self.showText(v, pos = 0, dp = [0, 1])

389

390 - def isAvailable(self):

391 ''' 392 Check if device is available. 393 @return: True, if device can be accessed 394 ''' 395 return self._isReady

396 397 # -------------------- private methods ----------------------------

398 - def _getData(self, pos):

399 if pos >= 0: 400 data = self._text[pos:pos + 4] 401 for i in range(4 - len(data)): 402 data.append(0) # spaces 403 else: 404 if 4 + pos >= 0: 405 data = self._text[0:4 + pos] 406 else: 407 data = [] 408 data.reverse() 409 for i in range(4 - len(data)): 410 data.append(0) # spaces 411 data.reverse() 412 for i in range(4): 413 data[i] = data[i] + 128 * self._decimalPoint[i] # add decimal points 414 return data

Source Code for Module py7seg