I am working on QGIS 3 project defined to UTM 34S EPSG: 32734 with some layers on WGS84 EPSG 4326.
I need to create a printable map on print composer with grids with DMS coordinates. The grid values (DMS values) must be shown on every exact degree and seconds interval with one minute jump. For instance: 20º34'30.000", 20º35'30.000", 20º36'30.000", 20º37'30.000"... and so on.
Since I need DMS coordinates and the project is using UTM 34S which uses meters, I have setup the grid to use the SRC EPSG: 4326 (WGS84). This way I can choose "Map Units" as Units Interval, and the grid Format as Degrees, Minutes, Seconds with 3 as the coordinate precision.
The problem is I cannot find the exact value to set on the field "Interval" (X/Y), in order to get a continuous value based on the one jump on the minute. The best I could make was to fit the degree and minute: 20º34', 20º35', 20º36'... not the seconds.
As you can see on the above image, degrees and minutes are as desired (with one minute "jump"). The seconds are not fixed and the problem resides here.
To be able to do it, I had found a value "0,016500000" as per above image, but cannot find the exact value that will allow me to fix the seconds issue.