Add preliminary STC8 support

What works:
* Frequency calibration of internal RC oscillator
* Flash/EEPROM programming

What doesn't work yet:
* Everything else

doc/stc8-protocol.txt

@@ -0,0 +1,133 @@
+Overview of changes
+-------------------
+
+The following changes have been observed compared to STC15:
+
+- Many differences in the status packet
+- At least some differences in MCS
+- Different challenge
+  - no separate program speed
+  - clock division was introduced; calibration always in the ~20-30 MHz range, lower clocks
+    use division
+  - the meaning of the calibration ranges and trim has changed
+
+The good:
+
+- Erase, Program, etc. operations are apparently unchanged. :)
+
+
+Status packet
+-------------
+
+46 B9 68 00 30   50 00 54 62 58 5D 00 04 FF FD 8B BF FF 27 4A F7 FE 73 55 00 F6 28 09 85 E3 5F 80 07 20 20 20 01 00 00 FE 05 3A 17 05 25 91 FF   10 AE 16
+                                                                                      ^^^^^ wakeup clock
+
+Clock set to 20 MHz by STC-ISP (encoding is different compared to STC15):
+
+46 B9 68 00 30   50 01 31 2E 90 38 01 01 FF FD 8B BF FF 27 35 F7 FE 73 55 00 F6 28 09 85 E3 5F 80 07 20 20 20 01 00 00 FE 05 3A 17 05 25 91 FF   10 54 16
+46 B9 68 00 30   50 01 31 2E 90 38 01 01 FF FD 8B BF FF 27 3B F7 FE 73 55 00 F6 28 09 85 E3 5F 80 07 20 20 20 01 00 00 FE 05 3A 17 05 25 91 FF   10 5A 16
+                                                        ^^^^^ some 24 MHz reference or other clk measurement?
+                                ^^^^^ trim/adjust?
+                                      ^^ clkdiv
+                    ^^^^^^^^^^^ clk
+
+
+Disconnect
+----------
+
+Uses FF command byte.
+
+
+Basic challenge operation
+-------------------------
+
+Host sends a challenge of some kind, followed by 0xfe pulsing
+
+46 B9 6A 00 0C   00 02 00 00 80 00   00 F8 16
+
+Much simpler than in STC15
+
+MCU sends back some response:
+
+46 B9 68 00 0C   00 02 36 AD 4E 83   02 2A 16
+
+Host now sends some longer challenge, followed by more pulses:
+
+46 B9 6A 00 20   00 0C 7C 00 7C 01 7C 02 7C 03 7D 00 7D 01 7D 02 7D 03 7E 00 7E 01 7E 02 7E 03   06 84 16
+
+MCU sends back some response:
+
+46 B9 68 00 20   00 0C 4D C6 4D DB 4D E7 4D F3 4D F6 4E 0E 4E 11 4E 26 4E 26 4E 32 4E 41 4E 56   09 DC 16
+
+Host now seems to initiate a baud switch or something like that
+
+46 B9 6A 00 0E   01 00 00 FF CC 01 7C 80   03 41 16
+
+MCU acknowlegdes it:
+
+46 B9 68 00 07   01   00 70 16
+
+Now the MCU switches to the new baud rate.
+
+
+Challenges observed
+-------------------
+
+6 MHz:
+
+46B96A0020000C 1400 1401 1402 1403 1500 1501 1502 1503 1600 1601 1602 1603 01A416
+
+5.5 MHz:
+
+46B96A0020000C 5C00 5C01 5C02 5C03 5D00 5D01 5D02 5D03 5E00 5E01 5E02 5E03 050416
+
+
+11 MHz:
+
+46B96A0020000C 5B00 5B01 5B02 5B03 5C00 5C01 5C02 5C03 5D00 5D01 5D02 5D03 04F816
+
+20 MHz:
+
+46B96A0020000C 3600 3601 3602 3603 3700 3701 3702 3703 3800 3801 3802 3803 033C16
+
+24 MHz:
+
+46B96A0020000C 7C00 7C01 7C02 7C03 7D00 7D01 7D02 7D03 7E00 7E01 7E02 7E03 068416
+
+27 MHz:
+
+46B96A0020000C B000 B001 B002 B003 B100 B101 B102 B103 B200 B201 B202 B203 08F416
+
+
+Ranges vs trim value
+--------------------
+
+46 B9 6A 00 20 00 0C   00 00  80 00  FF 00  00 01  80 01  FF 01  00 02  80 02  FF 02  00 03  80 03  FF 03   06 A4 16
+46 B9 68 00 20 00 0C   36 9B  4E 92  65 E4  36 CB  4E 7D  66 29  36 D1  4E 83  66 05  36 CB  4E C2  66 47   0A EA 16
+
+first byte determines general trim value... range of ~16 to ~30 MHz, the second byte (00..03) is a fine adjustment.
+
+
+Clock division?
+---------------
+
+5.5 MHz vs 11 Mhz: challenge is about the same. it's likely some kind of clock divider is used!
+
+5.5 Mhz switch: 01 00 00 FF CC 01 5C 80 clkdiv = 4?
+11  MHz switch: 01 00 00 FF CC 01 5B 80 clkdiv = 2?
+22  MHz switch: 01 00 00 FF CC 01 5C 80 clkdiv = 1?
+
+22 Mhz  option packet: 0400005AA5FFFFFF00FFFF00FFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00FF01516D405D0201FFFDFFFFFF8BBFF7FE
+11 MHz  option packet: 0400005AA5FFFFFF00FFFF00FFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00FF00A8AF985D0102FFFDFFFFFF8BBFF7FE
+5.5 MHz option packet: 0400005AA5FFFFFF00FFFF00FFFFFFFFFFFFFFFFFFFFFFFFFFFFFF00FF005462585D0004FFFDFFFFFF8BBFF7FE
+                                                                                             ^^ clkdiv?	
+                                                                                 ^^^^^^^^ clkspeed
+
+Always 24 MHz for programming
+-----------------------------
+
+Calibration for anything but 24 Mhz (and around that) fails when switching baud. Another observation is that there is no
+programming speed being calibrated anymore. This may suggest that a fixed speed is used for programming.
+
+Adjusting BRT calculation to 24 MHz in the switch packet seems to work. So it is really using 24 MHz by default;
+probably some pre-calibrated value.

stcgal/frontend.py

@@ -32,6 +32,7 @@ from stcgal.protocols import Stc12Protocol
 from stcgal.protocols import Stc15Protocol
 from stcgal.protocols import Stc15AProtocol
 from stcgal.protocols import StcUsb15Protocol
+from stcgal.protocols import Stc8Protocol
 from stcgal.protocols import StcAutoProtocol
 from stcgal.protocols import StcProtocolException
 from stcgal.protocols import StcFramingException
@@ -60,6 +61,9 @@ class StcGal:
         elif opts.protocol == "stc15":
             self.protocol = Stc15Protocol(opts.port, opts.handshake, opts.baud,
                                           round(opts.trim * 1000))
+        elif opts.protocol == "stc8":
+            self.protocol = Stc8Protocol(opts.port, opts.handshake, opts.baud,
+                                         round(opts.trim * 1000))
         elif opts.protocol == "usb15":
             self.protocol = StcUsb15Protocol()
         else:
@@ -216,7 +220,7 @@ def cli():
     parser.add_argument("-a", "--autoreset", help="cycle power automatically by asserting DTR", action="store_true")
     parser.add_argument("-r", "--resetcmd",  help="Use this shell command for board power-cycling (instead of DTR assertion)", action="store")
     parser.add_argument("-P", "--protocol", help="protocol version (default: auto)",
-                        choices=["stc89", "stc12a", "stc12b", "stc12", "stc15a", "stc15", "usb15", "auto"], default="auto")
+                        choices=["stc89", "stc12a", "stc12b", "stc12", "stc15a", "stc15", "stc8", "usb15", "auto"], default="auto")
     parser.add_argument("-p", "--port", help="serial port device", default="/dev/ttyUSB0")
     parser.add_argument("-b", "--baud", help="transfer baud rate (default: 19200)", type=BaudType(), default=19200)
     parser.add_argument("-l", "--handshake", help="handshake baud rate (default: 2400)", type=BaudType(), default=2400)

stcgal/protocols.py

@@ -372,7 +372,8 @@ class StcAutoProtocol(StcBaseProtocol):
                              ("stc12b", r"STC12(C|LE)(52|56)"),
                              ("stc12", r"(STC|IAP)(10|11|12)\D"),
                              ("stc15a", r"(STC|IAP)15[FL][012]0\d(E|EA|)$"),
-                             ("stc15", r"(STC|IAP|IRC)15\D")]
+                             ("stc15", r"(STC|IAP|IRC)15\D"),
+                             ("stc8", r"(STC|IAP|IRC)8")]
 
         for protocol_name, pattern in protocol_database:
             if re.match(pattern, self.model.name):
@@ -1546,6 +1547,123 @@ class Stc15Protocol(Stc15AProtocol):
         print("Target UID: %s" % Utils.hexstr(self.uid))
 
 
+class Stc8Protocol(Stc15Protocol):
+    """Protocol handler for STC8 series"""
+
+    def __init__(self, port, handshake, baud, trim):
+        Stc15Protocol.__init__(self, port, handshake, baud, trim)
+
+    def program_options(self):
+        # XXX: not yet implemented
+        pass
+
+    def initialize_status(self, packet):
+        """Decode status packet and store basic MCU info"""
+
+        self.mcu_clock_hz, = struct.unpack(">I", packet[1:5])
+        # XXX: external clock not supported nor tested
+        self.external_clock = False
+        # all ones means no calibration
+        # new chips are shipped without any calibration
+        # XXX: somehow check if that still holds
+        if self.mcu_clock_hz == 0xffffffff: self.mcu_clock_hz = 0
+
+        # pre-calibrated trim adjust for 24 MHz, range 0x40
+        self.freq_count_24 = packet[4]
+
+        # wakeup timer factory value
+        self.wakeup_freq, = struct.unpack(">H", packet[23:25])
+
+        bl_version, bl_stepping = struct.unpack("BB", packet[17:19])
+        bl_minor = packet[22] & 0x0f
+        self.mcu_bsl_version = "%d.%d.%d%s" % (bl_version >> 4, bl_version & 0x0f,
+                                               bl_minor, chr(bl_stepping))
+        self.bsl_version = bl_version
+
+    def calibrate(self):
+        """Calibrate selected user frequency frequency and switch to selected baudrate."""
+
+        # handle uncalibrated chips
+        if self.mcu_clock_hz == 0 and self.trim_frequency <= 0:
+            raise StcProtocolException("uncalibrated, please provide a trim value")
+
+        # determine target counter
+        user_speed = self.trim_frequency
+        if user_speed <= 0: user_speed = self.mcu_clock_hz
+        target_user_count = round(user_speed / (self.baud_handshake/2))
+
+        # calibration, round 1
+        # XXX: challenges need work. the ranges and how they related to clock frequency
+        # is different. A clock divider is used for lower frequencies.
+        print("Trimming frequency: ", end="")
+        sys.stdout.flush()
+        packet = bytes([0x00])
+        packet += struct.pack(">B", 12)
+        packet += bytes([11, 0x00, 11*2, 0x00, 11*3, 0x00])
+        packet += bytes([11*4, 0x00, 11*5, 0x00, 11*6, 0x00])
+        packet += bytes([11*7, 0x00, 11*8, 0x00, 11*9, 0x00])
+        packet += bytes([11*10, 0x00, 11*11, 0x00, 0x80, 0x00])
+        self.write_packet(packet)
+        self.pulse(b"\xfe", timeout=1.0)
+        response = self.read_packet()
+        if len(response) < 2 or response[0] != 0x00:
+            raise StcProtocolException("incorrect magic in handshake packet")
+
+        # select ranges and trim values
+        user_trim = self.choose_range(packet, response, target_user_count)
+        if user_trim == None:
+            raise StcProtocolException("frequency trimming unsuccessful")
+
+        # calibration, round 2
+        packet = bytes([0x00])
+        packet += struct.pack(">B", 12)
+        for i in range(user_trim[0] - 2, user_trim[0] + 2):
+            packet += bytes([i & 0xff, 0x00])
+        for i in range(user_trim[0] - 2, user_trim[0] + 2):
+            packet += bytes([i & 0xff, 0x01])
+        for i in range(user_trim[0] - 2, user_trim[0] + 2):
+            packet += bytes([i & 0xff, 0x02])
+        self.write_packet(packet)
+        self.pulse(b"\xfe", timeout=1.0)
+        response = self.read_packet()
+        if len(response) < 2 or response[0] != 0x00:
+            raise StcProtocolException("incorrect magic in handshake packet")
+
+        # select final values
+        user_trim, user_count = self.choose_trim(packet, response, target_user_count)
+        self.trim_value = user_trim
+        self.trim_frequency = round(user_count * (self.baud_handshake / 2))
+        print("%.03f MHz" % (self.trim_frequency / 1E6))
+
+        # switch to programming frequency
+        print("Switching to %d baud: " % self.baud_transfer, end="")
+        sys.stdout.flush()
+        packet = bytes([0x01, 0x00, 0x00])
+        bauds = self.baud_transfer * 4
+        packet += struct.pack(">H", int(65535 - 24E6 / bauds))
+        packet += bytes([user_trim[1], user_trim[0]])
+        iap_wait = self.get_iap_delay(user_speed)
+        packet += bytes([iap_wait])
+        self.write_packet(packet)
+        response = self.read_packet()
+        if len(response) < 1 or response[0] != 0x01:
+            raise StcProtocolException("incorrect magic in handshake packet")
+        self.ser.baudrate = self.baud_transfer
+
+    def initialize_options(self, status_packet):
+        """Initialize options"""
+        # XXX: not implemented yet
+        pass
+
+    def disconnect(self):
+        """Disconnect from MCU"""
+
+        # reset mcu
+        packet = bytes([0xff])
+        self.write_packet(packet)
+        self.ser.close()
+        print("Disconnected!")
+
 class StcUsb15Protocol(Stc15Protocol):
     """USB should use large blocks"""
     PROGRAM_BLOCKSIZE = 128