RTC board

[JimDrew]

That if says "navigate to /usr/share/zoneinfo/posix folder and find there the name of your place or time zone." How is this done? Under Linux? Through the SD card? If so, on a PC?

[NegSol]

I use an FTP client for this:
https://github.com/MiSTer-devel/Main_Mi ... ork-access

simply copy over and rename

[yellperil]

My build using parts from RS Components (Australia).

Capacitor Ceramic X5R 0805 10V 10uF
RS Stock No.802-9850

STMicroelectronics, M41T81M6F
RS Stock No.809-1420

Crystal 32.768KHz 2x6mm
RS Stock No.547-6979

Coin cell battery holder,SMT,low profile
RS Stock No.161-3707

Socket 2mm vertical 3mm lead 9+9 way
RS Stock No.779-2999

CRCW0805 Resistor T/R 0.125W,1%,4K7
RS Stock No.679-1496

[cvenditti]

What is the part # for temperature sensor on RTC v1.3?
Thank you
Cyril

[Sorgelig]

You don't need to solder Temp Sensor. It's optional and currently not used.
I've used P/N AD7415ARTZ-0500 on my board.

https://twen.rs-online.com/web/p/temper ... rs/5236276

[eris]

Sorgelig,

I was studying the RTC board and I'm trying to figure out how it works with the Minimig core. Obviously the M41T81 communicates with the Linux side via I2C. It updates periodically and via the hwclock command. How does the minimig pick up this date and time? Does it have direct access via some kind of FPGA to I2C bridge or is it getting it by asking Linux via NTP or some other interface?

Thanks,

eris

[Sorgelig]

MiSTer binary sends RTC info to cores among other info such as keyboard, mouse, etc.

[kolla]

MiSTer binary sends RTC info to cores among other info such as keyboard, mouse, etc.

I suppose writing to the clock from the Minimig is simply ignored (I have not tested).

[Sorgelig]

Right. You cannot set the time from cores.

[eris]

MiSTer binary sends RTC info to cores among other info such as keyboard, mouse, etc.

Is this interface documented or should I just read the linux RTC service code?

Thx

JimB

[Sorgelig]

There is no book of documentation if you mean this.
You can check hps_io.v signals. There you will find RTC info.
It would be more clear if you would tell what you want to do. Are you writing core which needs RTC?

[eris]

There is no book of documentation if you mean this.
You can check hps_io.v signals. There you will find RTC info.
It would be more clear if you would tell what you want to do. Are you writing core which needs RTC?

Ok, thanks. I was wondering what would be required if I wanted to use a different chip like the DS3231?

[Sorgelig]

It will require to add driver for this chip into Linux Kernel.

[eris]

It will require to add driver for this chip into Linux Kernel.

Okay. I see. The date-time service just formats the Linux date/time and passes it to the Minimig core, so you only need to change the Linux driver to support the new RTC chip.

[Sorgelig]

Okay. I see. The date-time service just formats the Linux date/time and passes it to the Minimig core, so you only need to change the Linux driver to support the new RTC chip.

right.
But i strongly suggest to use recommended chips. They are not hard to find and there is board already for them.
Otherwise you will have to modify and compile every new kernel release.

[eris]

Okay. I see. The date-time service just formats the Linux date/time and passes it to the Minimig core, so you only need to change the Linux driver to support the new RTC chip.

right.
But i strongly suggest to use recommended chips. They are not hard to find and there is board already for them.
Otherwise you will have to modify and compile every new kernel release.

Good point. I might use still use the recommended chip, but I'm trying to make a little proto-board that includes just the I/O and accessory devices I need. That should be easy enough.

[THaase]

As I don't like the Citizen Cylindrical Can type of crystal mentioned to work with RTC Board on the wiki page I would like to give a second working combination:

M41T81SM6F (Same as mentioned on the Wiki Page)
LCSC (alternative link to LCSC slightly cheaper)

together with:

Seiko Epson Q13FC1350000400 (+- 20ppm / 12.5pF / 70 kOhms )
LCSC
Digikey

I've some more RTC Chips here to test - so maybe I can provide some more working combinations later.

[Sorgelig]

The board originally designed for SMD crystals (what i'm using). Cylindrical crystals are adopted by other users

M41T81SM6F

does it work for you correctly? I had issue with M41T81S chip. Time runs out very fast in off state. May be it was just bad crystal/chip combination. M41T81 works well.

[cvenditti]

M41T81SM6F (Same as mentioned on the Wiki Page)
LCSC (alternative link to LCSC slightly cheaper)

Or super cheap (but might take 4 weeks to come ):
https://www.aliexpress.com/item/M41T81- ... 0.0.HpTzM8

[THaase]

does it work for you correctly?

Looks like having no issues (just running for some hours).
Let's see how it behaves over the weekend on battery.

[THaase]

Or super cheap (but might take 4 weeks to come ):
https://www.aliexpress.com/item/M41T81- ... 0.0.HpTzM8

Great - I'll give them a try (just ordered) - maybe without die

[THaase]

does it work for you correctly?

Looks like having no issues (just running for some hours).
Let's see how it behaves over the weekend on battery.

So running after 16 hours on battery still in sync.
Works fine I guess.

Next RTC Chips to try

[cvenditti]

You don't need to solder Temp Sensor. It's optional and currently not used.
I've used P/N AD7415ARTZ-0500 on my board.

https://twen.rs-online.com/web/p/temper ... rs/5236276

Can I use a AD7415ARTZ-1500RL7 (https://lcsc.com/product-detail/Tempera ... 43909.html) instead of the AD7415ARTZ-0500RL7

Thank you

[Sorgelig]

Generally speaking, no. They have different I2C addresses.
Currently there is no software support for temp sensor and i cannot tell if it will be easy to support different addresses or not.

[cvenditti]

Generally speaking, no. They have different I2C addresses.
Currently there is no software support for temp sensor and i cannot tell if it will be easy to support different addresses or not.

I just order some v1.3 pcb. I will wait more software support before start to do one.
Thank you