Hello there, I am designing a simple MIDI controller with a 16f628. For tho=
se who don't know MIDI communication is done through a 20 mA current loop.=
=20

The MIDI Standard Document states that you should put a buffer or an invert=
er after the micro's TX pin, depending by the capability of the micro to ru=
n with non-inverted/inverted output, so that the inverter could be a single=
 NPN in case of inverted output. However, the PIC USART module doesn't have=
 the inverted output mode so it needs a buffer to operate properly, accordi=
ng to the standard.=20

I assume that a buffer/inverter was needed because at the time microcontrol=
ler's IOs weren't able to supply/sink the 20mA needed by the current loop. =
In the datasheet of the 628 it's stated that each I/O pin can handle 25mA, =
is this true with alternated functions too?

If so, could there be any problem if i just connected the TX pin to the soc=
ket? on the transmitter there is +5V supply and the TX pin. on the Receiver=
 side it is an optocoupler with a resistor in series of one of the inputs. =
one of the input of the opto is connected to the +5V and the other to the T=
X pin

Jacopo
 		 	   		 =20
--=20
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