ZBasic Forum

Hi Guys

Well its been a long time since ive got the breadboard out, and its obviously showing.

Just trying to get a zx328n up and running, and cant get anything out of it.

I have....

Pin 1 going to DTR on USB-TTL and pulled up to 5v via 10k res
Pin 2 going to TX on USB-TTL
Pin 3 going to RX on USB-TTL and pulled up to 5v via 10k res
Pin 7 going to +5v
Pin 8 going to gnd
Pin 9 going to crystal with 27pf cap into gnd
Pin 10 going to cystal with 27pf cap into gnd
Pin 20 going to +5v
Pin 22 going to gnd

gnd on USB-TTL going to gnd

com port is set to standard 19200 but nothing.

what am i missing?

Cheers

Ben

sturgessb wrote:Pin 1 going to DTR on USB-TTL and pulled up to 5v via 10k res

You need the ATN circuit (transistor, capacitor, resistors) between DTR and pin 1. See http://www.zbasic.net/doc/ZBasicRef.php?page=189.

The other connections look fine.

hi don

thanks for this, although im now getting data though its all gibberish no matter what the baud

ben

is the diode on the transistor essential?

sturgessb wrote:is the diode on the transistor essential?

No. It is only needed if the DTR signal goes below 0 volts as it does on a standard RS-232 port. Since you're driving the ATN circuit with the DTR ouput of the USB-TTL converter, the signal swing is going to be 0-5 volts.

Can you download a new program to the device?

no, failed to respond to atn,

if i select 'reset device' its definately resetting. but the ide cannot detect the device type either

this is an image of the output im getting... http://tinypic.com/r/6is9cy/5

Hi Ben,

I strongly believe that the issue is that all of the signals may / may not need to be inverted (depending on your hardware of course), as I had exactly the same type of ZX328 response. The FDTI chips have the programmable option for inverting the RxD and TxD and DTR signals, you could try to change the settings (see the USB-TTL interface device document). If the device can be reset from the IDE then that part works fine and thus the DTR signal setting should not be changed, I think.
I finally cleared the matter out with the help of Don but I did not save the mail conversation.

Good luck, you are almost there!

/Jurjen

Cheers for the tip, mr Becker also suggested inverting, so I tried this via the f-prog app. Still the same result

ben

right, that inverting did fix it. its just i needed to unpower the USB-ttl to get it to operate in new mode.

cheers

Great result, you were close ;o)!

/Jurjen