I have a good USB-serial converter cable that works well with other types of devices (not tested with other microcontrollers), but it works only intermittently for downloading. The bable uses an FTDI chipset, thought I am not sure which one.

I usually get a message in red letters about the connection being broken, or something similar. If I keep retrying to download, it will eventually work.

Any ideas about what to do to get it to work?

-Tony

I have reproduced your problem with my USB-serial cable. What I found is that the problem only occurs if the port is closed. If you open the port as though you wanted to view the console and then try the download it works.

When the port is closed, the download procedure opens the port, performs the download and then closes it again. Can you let me know if this workaround works for your cable?

My guess is that there is a timing issue and perhaps some "settle time" is needed. I will investigate a solution. The Reset button seems to work ok with my cable whether the port is open or closed.

Mike wrote:
I have reproduced your problem with my USB-serial cable. What I found is that the problem only occurs if the port is closed. If you open the port as though you wanted to view the console and then try the download it works.
Mike,

This time I was getting almost no communication with the device thru the USB cable. Downloads would occasionally act as if they went through, but the program was not actually updated.

Even the console was hit or miss. Resets do not seem to get through.

-Tony

Here is a key statement from your first append:

I have a good USB-serial converter cable that works well with other types of devices (not tested with other microcontrollers)
Does this cable indeed work with other devices?. I would try a ZX-24ae first.

No, it ZBasic crashes and burns horribly when I attempt to "GO".

I guess that not all FTDI-based units are equally good.

I am not sure of the brand of this one. It seemed hard to me to find a serial-USB converter that was specifically identified as FTDI-based. Most of those that do identify the hardware do not use FTDI.

What brand cable do you use/recommend? I assume that it works with the ZX's?

-Tony

I have two. One is a no-name "Made in China". I cannot remember where I bought it from. We do have a local Frys store and I think I got it from there.

The other is a Elba Corp USB-TTL. converter.