ZX-40 versus the BX-35

[G Herzog]

I have Netmedia's Development board that includes a socket for the BX-35.

Is the ZX-40 the configuration on a pin-to-pin basis?

If so, it would make using one much easier as I already have an operational setup.

[dkinzer]

Is the ZX-40 [compatible with the BX-35] on a pin-to-pin basis?

Although I have not done so, I believe that you can get the ZX-40 to run in the BXDS-24 with some minor changes. Firstly, the existing crystal (7.37MHz) needs to be replaced with a 14.7456MHz crystal (e.g. Digi-Key X175-ND). Secondly, a different ATN circuit needs to be used. This can be most easily done using two jumpers. The first jumper would connect between the square pin connected to pin 2 of the BX-35 socket to the IN1 square pin. The second jumper would connect between the OUT1 square pin and the square pin attached to pin 9 of the BX-35 socket. For best results, there should be a resistor (perhaps 10K to 47K) in series with the second jumper. Without the resistor, the reset button will short the output of U8A to ground.

An alternate strategy that might work is to remove the jumper block from J1 and connect a jumper from the center pin of J1 to the square pin that is connected to pin 16 of the BX-35 socket. This method will render the reset switch useless, however.

I can also send you a prototype ZX-40 interface board that makes prototyping very easy.

[Edit: changed the modification description of the first method above to correct a pin number. Thanks to drapal for sleuthing this out.]

[G Herzog]

Thank you for the thoughtful reply.

At first glance, it looks deceptively simple. Nonetheless, I am please to see it is 'doable' if I choose to make the modifications.

I certainly will take a look at the ZX-40 interface board, but the two ZX24s are keeping me busy enough at this time.

In sum, this was for future reference as the ZX40 offers more I/O if and when I really need it.

[G Herzog]

This 2nd posting is intentional [for emphasis].

I took a look at the Z-40 interface board and was quite pleasantly surprised. It is by far cleaner and more convienent than what I have been trying to impliment or use.

Is it on-sale? I don't see it amongst the products listing.

[dkinzer]

Is [the ZX-40 interface board] on-sale?

It's not available as a product at this time. I have a few of the prototype boards available. They don't have solder mask or silk screent (just as shown in the picture) but they are quite usable. I can send you one if you'd like. You'll need to get the parts and assemble it yourself. I will include the square pins, though, if you don't have any.

[drapal]

I thought this might be a quick way to get started since I am coming from a BX-01 enviironment and had the BX Dev board to work with. I tried both of the suggested ATN mods and neither seem to work. I see the "ZBasic 1.1.2" banner come out on the port when I reset the processor, so I know the port config is correct, but when I try to download, I get "Device failed to respond to ATN signal on COMx.". Tried a hard-wired and a USB COM port and got the same results.

Any other suggestions? I sure would like for this to work, as I have some hardware in the work area of the Dev board I'd like to have access to (e.g. a SitePlayer ).

[drapal]

THE problem is that the BSDS schematic is *wrong*! On the BX-35, Pin 2 is the ATN pin, not pin 16. I should learn to trust the buzz-meter ...

Anyway, if you make that change to the instructions and use the first suggested modification (pin 2 to IN1, OUT1 to Pin 9) things work like a champ.

[dkinzer]

Thanks for the update. I'll change the modification description.

[drapal]

I had this working in April. Now that I get back to it (getting serious now ), I can't seem to get anything to download. I always fail at record 1 in the verification pass. I've run the ATN test, and the voltages are OK at the ATN jumper, and I verifyied that Pin 9 toggles as it should. The interesting thing is the download claims to work, the verification always fails and I get the "ZBasic 1.1.2". Hitting the reset button repeats the ZBasic prompt, so I'm failry sure that the dev station board is OK and functioning. I've tried 2 different COM ports, and at least two different cables. Also have tried 3 diferent EEPROM parts - don't think they are all bad. I don't know what to try next - Help!

[dkinzer]

If the error only occurs on the verification pass then it would seem that the communication is OK. Each record (1 to 16 bytes) has a checksum on it so it can catch some kinds of communication errors.

I suspect that something is awry with the EEPROM or the connection to it.
If you have a logic probe, you can probe the CS pin of the EEPROM during download. It should be changing states.

If you're using a 32K EEPROM, it is important to note that the AT25256 part with out the A suffix is too slow to operate reliably withe the ZX; it does work OK with the BX because it is slower. It may work one day with the ZX and not the next. You'll need an AT25256A for reliable operation.

If you're using a 64K EEPROM (AT25HP512) that has been previously written by the BX, that is a problem that was resolved in v1.2.0 of the VM (you have v1.1.2). The BX write-protects the 64K EEPROM after it programs it.

[drapal]

If you're using a 64K EEPROM (AT25HP512) that has been previously written by the BX, that is a problem that was resolved in v1.2.0 of the VM (you have v1.1.2). The BX write-protects the 64K EEPROM after it programs it.

Looks like you might have hit the nail on the head here - All three parts I tried were originally in a BX-01 configuration.

Now for the second part - I tried (last night) to upgrade the VM to the latest. Again, seems that it won't work - CRC error, if I remember correctly. Is there a way to "force" the VM update?

[dkinzer]

I tried (last night) to upgrade the VM to the latest. [It didn't] work - CRC error, if I remember correctly. Is there a way to "force" the VM update?

If it reported a CRC error, that suggests a communication problem - some of the data was transmitted or received incorrectly. I assume that you're attempting the update using the BasicX Dev board. I've not done that before but, off hand, I can't think of a reason why it wouldn't work.

You could try the emergency update procedure described in the manual but if there is a problem with the serial interconnect I doubt that that would be any more successful. I would recommend confirming all of the connections and retrying the normal update procedure, carefully noting the error message.

[DH*]

FWIW, I've had no problems whatsoever downloading either the VM or my application firmware to a ZX-40 and a Catalyst CAT25C256XI-G EEPROM on my own board design. I've tested both several times because of earlier problems I had when trying to update the ZX-24 firmware. It is, however, screwing up my life and making me irritable as I was accustomed to taking a pee break, refilling my coffee cup and catching up on my email while waiting for my firmware to download to a BX-24. ZX downloads are way too fast for that.

IOW, I think any problems you are having are related either to the EEPROM you are using or to the development board.

[drapal]

The firware upgrade fails with the following:

Updating device firmware using file "C:\Program Files\ZBasic\zx40_1-2-0.zvm":
Retry limit exceeded, aborting update.
ZBasic v1.1.2

Now what do I try? THE emergency recovery procedure?

[drapal]

zload -c1 -e zx40_1-2-0.zvm

zload crashes, attachment is the exception info.