Extensible Multiple Device Programmer 1

The power supply takes its power from a 24-volt VDC wall wart either via N1, an on board connector, or via N10 an off-board connector. The power switch is either mounted on board or off-board via connector N2. The fuse can either be on board at F1 or off board via connector N3. Diode D1 is a shorting diode that should short the supply and burn out
Extensible Multiple Device Programmer 1 - schematic

the fuse if the power supply gets hooked up backwards. The 24VDC is regulated to 24 volts via C1, U1, and C2. The 24Volts is regulated down to 15 volts via U2 and C3. The 15 volts is regulated down to 5 volts vis U3 and C4. N is available if people wish to provide an source of power supply voltages and leave U1-U3 empty. The EMDP1 can communicate with its host processor via either RS-232 or RS-422 signaling. The RS-232 signaling takes place via an industrys standard female DB9 connector. The RS-422 signaling done via an RJ45 connector using standard Cat5 (catagory 5) cabling. The RS-422 is wired to conform to my SimpliciNet `standard`, which allows both RS-422 signalling and power over the same cable. The RS-232 signals are converted to logic levels using U3, a standard MAX232 level convert chip. U4 is an RS-422 transceiver configured as an RS-422 transmitter and U5 is an RS-422 transceiver configured as a receiver. Resister R7 is 100 ohms of RS-422 termination and R8 and R9 provide biasing resistors to ensure that a logic high level is output if now RS-422 signal is present. U6A is takes the logical or of the received signals from the RS-232 and RS-422 and sends them on to the microcontroller serial receive line. U6B logically or`s the transmit signals from the adaptor (via U11A) or from the microcontroller (MTX). R27 is forces the adaptor signal out if the microcontroller chip is being programmed by the bootstrap...

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