MKR 1010 + RS485 shield

Hardware MKR Family MKRWIFI1010
1

Hello!

I'm looking for some clarity on the MKR RS485 shield. The documentation is sparse, and the only example I can find on the web (while helpful) doesn't go into the detail I'd like.

First, there is some ambiguity over the pins. The RS485 shield Getting Started page describes the following pin assignment:

A4 RE
A5 DE
13 RX
14 TX

However the official Arduino RS485 library has the following defaults (described on the Set Pins function description):

By default the library uses pin 14 for TX, pin A6 for drive output enable, and pin A5 for receiver output enable.

On the shield schematic A5 looks to be RE and A6 looks to be DE, so that concurs with the library, but not the product getting started page.

Can anyone confirm this for me?

Next, the Maxim datasheet suggests that RE should be LOW to receive, and DE should be HIGH. (So I could use a single pin on the micro, if the shield didn't force me to use two.) Am I reading that correctly?

I actually want to use a different library - ModbusMaster - as I have some code I previously wrote that works with it (I'm trying to adapt my code from uno + DFRobot shield to MKR format), so I'd just like some confirmation on this before I get confused and implode as I need to set the RE and DE pins and states for the library to work.

Many thanks in advance for your help!

If there are errors in the getting started page (as I suspect), how can I get it updated? I don't have an option to edit the page.

2

Hi. Thanks for reporting this issue. I don't own one of these shields to check, but it does seem more likely that the Getting Started page is wrong, rather than both the schematic and library documentation being wrong.

Have you tried doing a continuity test between the shield pins and the MAX3157 pins to verify that the schematic is correct?

marksw:
If there are errors in the getting started page (as I suspect), how can I get it updated? I don't have an option to edit the page.

It is unfortunate that there is not a way for contributors to directly edit the contents of much of the Arduino documentation. However, you are welcome to submit reports of errors or suggestions for improvement to the general documentation here:

If there is an error for the documentation for a specific library (probably not in this case), you can submit the issue report to the repository for that library:

Please take a minute to do a search of the existing issue reports before submitting one to make sure the same issue hasn't already been reported. I already did a search for this particular issue and it has not yet been reported.

Helping to improve the documentation is a very valuable contribution to the Arduino project. Thanks!