In the diagram, the red arrows show the data bus, and blue - power supply units.
he scheme is simple, but there are nuances: a diode VD1 - fast (if you use the chip IR2153D it is not required), suppressor VD4 and VD15 are necessary to protect the rectifier diodes, if they are selected without a large supply of voltage. Transformer Tp2 made three put together ferrite rings size 20h12h6 2000NN: primary winding contains 70 turns of 0.3mm, low-power secondary winding (for supply IR2153) - 2 sections of 7 turns of the same wire (two wires dangle, then the beginning of one wire is connected with the end of the other and get the average point - as usual), a powerful secondary winding - 2 Section 7 turns of three wires braid 0.5mm (6 wires shakes, then divide in half, etc. - as well as with low-power). Do not forget the interlayer insulation!
To supply the gas-discharge indicators require a high voltage source of the order of 200V needed for ignition and maintain a stable level in the indicator. Upconverter 12 -> 200V is made on a chip MAX1771:
In the high-voltage part of the circuit elements should be used to withstand appropriate voltage. Divider formed by resistors R2, R3 and variable resistor sets the output voltage, which can be adjusted within certain limits. In my case, the output voltage is 190V, which is sufficient for the indicators. Inverter power is sufficient for simultaneous operation of all six indicators. On the left - a 5-volt converter to the right - increases.
USB module to the FT232BM is a separate fee, vertically soldered into the main. Module is assembled on the template except for the missing chip EEPROM:
At the same time can only run one of the COM interfaces or USB, with preference given to USB, because switching is realized by means of the relay, energized from the connector USB: sticking with cable relay will spread and go to the controller data from the module FT232.
It is connected only to additional charges decoder, the main board yet. Thus, the constructs with little understood, now a few words about the firmware.
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