Board for the zx 24a

Discussion specific to the 24-pin ZX microcontrollers, e.g. ZX-24r, ZX-24s and ZX-24t.
dlh
Posts: 395
Joined: 15 December 2006, 12:12 PM
Location: ~Cincinnati

Post by dlh »

GTBecker wrote:In addition to the many boards available, I submit an easy way to get to see Hello World and you can go from there.

The connector is a DB9M (a male, opposite of the usual DB9F), with a F-F gender changer on it to make it a female. The combination of the two makes a reverse-pinout female whose pins 2 to 5 line up with processor pins 1 to 4. A reset switch (this uses a jumper) and power is all you need to talk to the machine.
Winford Engineering makes breakout boards and breadboard adapters for the most common connectors. Their prices are quite reasonable. Circuit Specialists has the same high quality breadboards several people have mentioned, including a large one with built-in +5V, +15V & -15V power supplies for a reasonable price. The +5V supply is fixed; the 15V supplies are variable. Spark Fun has a 5/3.3V supply that plugs into a breadboard.Tom: Check your spam filters. I responded to your recent emails but suspect you never received my replies.
GTBecker
Posts: 616
Joined: 17 January 2006, 19:59 PM
Location: Cape Coral

Post by GTBecker »

Parallax's Propeller Plug can be used to control nX-24 processors via USB with a simple (but very small) modification.

As supplied, the Plug's /RES pin yields an open-collector active-low pulse when the onboard FT232R DTR# pin goes high. Even with a pullup, that won't successfully act as ATN. It's easy (with small tools), though, to remove a 10nF series capacitor and connect the DTR# output through an (optional) 150ohm resistor to the module's /RES pin. That provides a level output for ATN control. +5v can also be taken from the USB connector to power the processor, within 100mA total.

FTDI's current MProg v2.9c can program the FT232R outputs to either sense; I found that inverting all three (TXD, RXD, DTR#) works correctly. You can also change the Product Description field to rename your custom USB adapter module.

The photos show a BX-24p because the ZBasic IDE would not open the USB port until I removed an old version of both the IDE and the drivers; the ZBasic IDE now works fine with this device.

FYI.
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Tom
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