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Step 6Prototype - USB
The display and CPU part is running, so it was time for the USB part. The FT232R is a SOIC28 chip where the pins are at 0.68 mm CC (0.026 inch) and I didn't have an adapter board for it. Manually soldering wires to the pins is possible is you have the right soldering tip, a good soldering flux and a really good magnifying glass, but I didn't have anything is these so I decided to do it another way.
I bent every other pin up and the others down on the chip. This way I increased the spacing between the individual pins I had to solder to something like 1 mm - and that I could handle.
By soldering wire-wrap wires on the pins and then soldering them to a standard IC socket I had my adapter. A quick optical inspection didn't reveal any short circuits, but with such small dimensions and tight tolerances I could easily miss a few bridges.
I inserted the socket into the proto board, connected the capacitor for the internal 3.3 volt generator in the chip and applied power to it. I measured 3.4 volt over the capacitor so the chip was at least partly alive.
After connecting the D+ and D- from an USB cable to it the computer told me that an "Unknown USB device had been connected to it.". This is bad news since XP already got the drivers for the FTDI-chip it it. Hmmm... Maybe I just connected the D+ and D- wires the wrong way around even if I had checked it before I connected them. And yes, that was it. After I reversed them the computer identified the chip and a new serial port.
I looped the TXD and RXD pins together and I got the text I wrote in hyperterminal echoed back to me. Hooray! It's working....
I used an utility from FTDI to set the CBUS1-pin to output 6 MHz to drive the ATTiny2313 with. And then a downloaded a serial port testing program so I could manually toggle RTS and DTR on the chip so I could check that those outputs was working. I also tested the inputs like CTS, RI and CD.
I'm really amazed that it all worked, but I think that I need to dip the entire thing in hot glue in order to not getting it destroyed by just looking at it. It looks really ugly and fragile.
I bent every other pin up and the others down on the chip. This way I increased the spacing between the individual pins I had to solder to something like 1 mm - and that I could handle.
By soldering wire-wrap wires on the pins and then soldering them to a standard IC socket I had my adapter. A quick optical inspection didn't reveal any short circuits, but with such small dimensions and tight tolerances I could easily miss a few bridges.
I inserted the socket into the proto board, connected the capacitor for the internal 3.3 volt generator in the chip and applied power to it. I measured 3.4 volt over the capacitor so the chip was at least partly alive.
After connecting the D+ and D- from an USB cable to it the computer told me that an "Unknown USB device had been connected to it.". This is bad news since XP already got the drivers for the FTDI-chip it it. Hmmm... Maybe I just connected the D+ and D- wires the wrong way around even if I had checked it before I connected them. And yes, that was it. After I reversed them the computer identified the chip and a new serial port.
I looped the TXD and RXD pins together and I got the text I wrote in hyperterminal echoed back to me. Hooray! It's working....
I used an utility from FTDI to set the CBUS1-pin to output 6 MHz to drive the ATTiny2313 with. And then a downloaded a serial port testing program so I could manually toggle RTS and DTR on the chip so I could check that those outputs was working. I also tested the inputs like CTS, RI and CD.
I'm really amazed that it all worked, but I think that I need to dip the entire thing in hot glue in order to not getting it destroyed by just looking at it. It looks really ugly and fragile.
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