Newbie Q: Datalogger Rev B and MKR1000

[CarlFisher]

This is my first Arduino project, and first electronics project at all TBH. I have my project working on a Mkr1000 but now I want to log the data.

The pins don't line up between the Arduino and the datalogger shield, so my question is what wires do I need to connect? I've got 5V, Gnd,
SCL, and SDA hooked up already. What about CS on the logger? Would that go to SS on the processor?

Anything else?

[mikeysklar]

@CarlFisher,

Did you see the Rev B Shield Pinouts? Make sure to cut the Vio jumper to 5v on the datalogger shield with the MKR1000. You want everything at 3v.

https://learn.adafruit.com/adafruit-dat ... -1948736-6

Rev B Shield Pinouts
ICSP SCK - SPI clock
ICSP MISO - SPI MISO
ICSP MOSI - SPI MOSI
Digital #10 - SD Card chip select (can cut a trace to re-assign)
SDA not connected to A4
SCL not connected to A5
The RTC (PCF8523) logic level can be 3V or 5V

On an UNO, note that Digital #13 is the same as ICSP SCK, #12 is ICSP MISO, #11 is ICSP MOSI, SDA is tied to A4 and SCL is A5. However, that is only true on the UNO! Other Arduino's have different connections. Since the shield no longer makes the assumption it's on an UNO, it is the most cross-compatible shield.

On the bottom of the Rev B shield, you can see that if you have an older Arduino where there is no ICSP 2x3 header, and no SDA/SCL pins, you can short the solder jumpers closed.

[CarlFisher]

Thanks @mikeysklar,

I thought I could power the datalogger by putting 5V to the 5V bus. No?
The doc says

... Built in 3.3v level shifter circuitry lets you read or write super fast and prevents damage to your SD card

So I should cut the Vio trace on the logger, solder it to 3V, and bring 3V from the MKR to Vin on the shield instead?

I read the documentation at first to say I could communicate with the SD card via I2C or SPI, but on a second reading it looks like I have to use SPI for the SD card.

The doc also says (on the Installing the Header page)

Both options additionally require (their emphasis) a 2x3 female header soldered on.

So now I think I see I need to connect the MKR to the shield through the ICSP holes, or else short the SPI jumpers on the shield and use holes 10-13- right?
Hmm, but one of the ICSP connections is for 5V- should I supply 3V instead?

As you can see, I'm still learning the conventions that make this stuff easy for y'all. I appreciate your time and patience in helping me get up to speed! I am enjoying my first Arduino project, and it's really great that there are so many resources available to those of us starting out.

Thanks again!

[mikeysklar]

The Datalogger has a 3v regulator so it can handle 5v input. The is a suggestion on the Wiring & Config page about cutting the Vio jumper if you are using a 3v based Arduino which your MKRZero is. I would cut the Vio jumper as suggested and power ideally from 3v, but 5v through the 3v datalogger regulator would be safe.

If you are using the shield with a 3.3V logic Arduino, you may want to change the Vio jumper. This is what the 10K pullups for I2C are pulled up to. Honestly, the pullups are very weak so if you forget, it's not a big deal. But if you can, cut the small trace between the center pad and 5V and solder the other side so that Vio is connected to 3V

https://learn.adafruit.com/adafruit-dat ... and-config

SD card communication will always be SPI based (at least in all the versions I have seen so far). The RTC (real-time clock) is I2C based and mentioned frequently which could have been the source of I2C confusion.

You should keep all your connections 3v to reduce the risk of blowing out a GPIO pin. The ICSP header is often used on shields with modern Arduino boards. You can post a photo and/or drawings of what you are connecting if you need more guidance.

[CarlFisher]

Got it working. Brought over all the ICSP wires and shorted the Vio pad to 3v and it was good. Used pin 7 for chipselect.

Thanks for the help!

[mikeysklar]

Good job and thank you for the followup. Happy hacking.