It is the Wild, Wild West out here in New Mexico; people still shooting off their guns on New Year Eve. So I'm staying indoor to work on a few projects. Three interesting parts just came in from Mouser: DS1086 EconOscillator controllable via I2C; ZDU0110 I2C UART also controllable via I2C; and W65C134S8PLG-14 allegedly a 14MHz 6502-based micro-controller.
Proxy has a pc board for DS186, but it is simple enough to wire one up. ZDU0110 I2C UART has 0.65mm pitch, right at the limit of my bread-boarding capability; and I plan to overclock W65C134 past 14MHz.
Bill

After my own experiments with the '134 and getting it to boot directly into my TinyBasic, I wish you the best of luck.

The '134 already has a UART on-board, however it will really only work with certain clock frequencies as anything else doesn't divide well for recognisable baud rates. (This may be why you're using an external uart though)

You have RAM from $40 to $FF and the same RAM from $0140 through $01FF, but a lot of it is used by the on board ROM monitor. If you want to use those I2C UARTs you'll need to add RAM, download your own code into it (via the on-board UART) and run it from RAM. Fortunately the on-board monitor will detect the extra RAM and enable it at boot time (which removes the mirroring of page 0 and page 1), then you can use it's SREC download facility to get going (over the internal UART)

And/or add ROM/Flash/EEPROM and run your code from that - after the on-board ROM starts up. (It looks for a signature at $8000)

And/or do some magic shenanigans with the BE signal at reset time to totally disable the on-board ROM and have your own ROM (Flash/eeprom/etc.) take-over.

I think you may need 2 oscillators for the '134 too - it starts on the slow one (typically 32K) then you can switch to the fast one under software control. I never did work out if you could plumb a fast oscillator directly into the slow input pin.

Have fun - but I fear it will take several new years eves worth of days to get it going

-Gordon

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Gordon Henderson.
See my Ruby 6502 and 65816 SBC projects here: https://projects.drogon.net/ruby/

Thanks for the tips. Your recent posts about your experiences with W65C134SXB is the motivation for me to look into 65C134. I'll definitely refer to your posts for potential pitfalls with this chip. I have several small projects ahead of 65C134 so I don't think I'll think much about it by New Year Eve. I'm waiting for a batch of boards back from JLCPCB; one of them is the experimental platform for 65C134 which is not based on Western Design's W65C134SXB. It has '134, RAM, CPLD, and CF interface with the goal of exploring the upper limit of 65C134.

Meanwhile I've breadboard up a ZDU0110, I2C UART. 0.65mm pitch is definitely limit of my prototyping ability. It is an interesting device that's useful in situation when clock frequency is changing as in overclocking experiment.
Bill

I'm not getting anywhere with I2C UART. It responded correctly to the I2C address, but I'm unable to get it to send/receive data or toggle the general IO pins. Does anyone has experience with ZDU0110? Right now I'm putting it to the back burner waiting for an epiphany...

Next I worked on DS1086 EconOscillator because it is a simpler circuit and easier to prototype. This way I'm also checking out my test platform which is CRC65 with a proven I2C port. DS1086 prototype worked perfectly, just as advertised. It is really a cool adjustable oscillator replacing about 2 dozen oscillators I have on the shelf.

Bill

Cool - yes it is a useful part. It looks like you have connected SPRD low - how consistent is the output frequency in that configuration? I connected it high, as shown in the example circuit in the datasheet, and was uncomfortable with the degree to which the output frequency then varied.

This looks like a really nice device, Bill.

When I get stuck on a new (to me) device there always seems to be Arduino examples to study. I'll often test the device with the Arduino examples then go back to work fixing my code/drivers. The github for this ZDU0110 module looks promising.

Happy Holidays. Mike

The waveform looks very stable with SPRD pulled down. I can turn on the "storage" function on my scope and see only a clean trace without jitter.


Thanks for the link, very interesting that there are 10 pull-up resistors. I only have two.
Bill