Does anybody know the serial protocol or the model of the main controller chip and USB interface chip inside?

Disclaimer|: I have obtained the following info by observation and experimentation and so I don't guarantee it is correct or complete. BOLYFA 117 technical description Circuit The Bolyfa 117 is based on the Hycon Technology DTA0660L single chip DMM IC. This connects via an SPI interface to a HY11P14 microcontroller which drives the LCD and also a free space opto-coupler which sends data to a CH340G serial to USB converter. The 6V battery is regulated down to 3.3V by a HT7533-1 low drop out linear regulator. A T24C02A EEPROM is also provided to store 256 bytes of calibration data. USB interface An opto isolated USB connector is provided which permits the readings and current settings of the meter to be read remotely. This interface is one way only and, after a long press of the REL/USB button the meter starts to send out a constant stream of 22 byte frames at a rate of 5.2 frames/s. The bytes hold the LCD segment drive data and therefore must be decoded to obtain meaningful data. The frame format is as follows; Bytes 0 to 5: Fixed pattern = AA 55 52 24 01 10 Bytes 6 to 9: These are the four display digits, in seven segment format Byte 6 = least significant digit Byte 9 = most significant digit When the digit is preceded by a decimal point this adds 128 to the value. The table below shows the hex value of the each byte and the text that should be substituted in order to build up a string representing the display. (NB when overload occurs O/L is displayed which is not shown in this table). Hex Text 5F 0 06 1 6B 2 2F 3 36 4 3D 5 7D 6 07 7 7F 8 3F 9 DF .0 86 .1 EB .2 AF .3 B6 .4 BD .5 FD .6 87 .7 FF .8 BF .9 The Hex bytes are converted to a text string representing the display using the table above and starting with byte 9 Eg a byte 6 to 9 sequence 2F 3D DF 06 represents the display value 1.053 Byte9 = 06 = 1 Byte8 = DF = .0 Byte7 = 3D = 5 Byte6 = 2F = 3 Join them together to give text string = 1.053 then convert to a floating point number if required Byte 10: 0x24 = DC (with +ve reading) 0x2C = DC (with –ve reading) 0X22 = AC 0x00 = No indicator Byte11: 0x01 = Voltage present and range correct 0x00 = Voltage absent or manual range incorrect 0xFF = Over range Bytes 12 to 17 These six bytes are all 0x00 for normal operation and 0xFF for over-range (The lower 4 bits of byte 19 are also 0x0 for normal operation and change to 0xF for over-range) Byte 19 Byte 20 Byte 21: 01 00 08 = Volts 03 00 08 = Volts MAX 09 00 08 = Volts MIN 00 08 0F = Volts MAX-MIN (this repeats for other measurements but not shown in this table) 01 00 0A = mV 01 00 80 = Hz 21 00 00 =% 01 00 60 = kOhms 01 00 50 = MOhms 01 00 40 = Ohms 01 A0 00 = Capacitance 01 01 00 = Temp C 01 02 00 = Temp F 41 00 00 = HFE 01 00 05 = uA 01 00 06 = mA 01 00 04 = A Setting up the virtual COM port The USB interface is based on the CH340G virtual COM port. In Device Manager identify which port has been selected. Then for that port select the ‘port settings’ tab and set to; Bits per second = 2400 Data bits = 8 Parity = none Stop bits = 1.5 Flow control = none Tip: Clear the buffer immediately before taking each reading otherwise you get significantly out of date values.

Manufacturer	Vorstik
Part Number	BF117
Package Dimensions	30 x 15 x 7 cm; 840 g
Batteries	2 AAA batteries required. (included)
Manufacturer reference	BF117
Colour	BF117
Style	Modern
Power Source	Battery Powered
Item Package Quantity	1
Special Features	DC Voltage (V): 60mv/600mV/6V/60V/600V ±(0.7%+2), 1000V
Batteries included?	Yes
Batteries Required?	No
Item Weight	840 g

Digital Multimeter, BOLYFA Advanced TRMS Auto Ranging Multimeter USB;Ammeter;Voltmeter;Ohmmeter;Current/Resistance/Capacitance/Frequency/Diodes/Transistors/Temperature/Continuity/LCD Backlight

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