Member Since: October 6, 2008

Country: United States

  • What does this do that the $10 cypress dev board CY8CKIT-059 doesn't?

  • This is an old hack. Back before charge pump style RS232 chips were a thing, you needed a -5 or -12V supply for your RS-232 driver. The MC1489 receiver chip (your grandpa's 232 RX chip) would work with a signal that went between 3V down to about 1V (it only need a plus rail and ground) so you could drive an RS232 input with a TTL gate and save having a negative supply rail. I believe most of the newer RS232 chips work the same way as the MC1489. The hack won't work under all conditions a real 232 driver will, but for bench stuff over a few feet with a known receiver, it works fine.

  • While cheap, these style of holders are a PITA. They rely on good contact between the battery and a solder pad on the PCB for one side of the circuit.
    We used them on a production basis and we had many problems with contaminants making a bad connection. Finally ended up manually swabbing each board before it went out. Do yourself a favor and get a holder with two contacts.

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