View source for OpenMower Unicore GPS

Several users have chosen alternative GPS RTK modules with chips by ''Unicore'':

* ''UM960''
* ''UM980''
* ''UM982''

These chips are sold in different variants. Some come with a USB-C socket (so they can be connected directly to the Raspberry Pi). Some have different antenna socket (which need an ''SMA F'' to ''MMCX M90'' cable).

Compared to the ''ArduSimple simpleRTK2B,'' they're a bit cheaper and support triple-band frequencies.

== Variants how modules can be connected and configured ==
* Connection
** Module USB-c -> RPI USB (e.g. with angle connector)
** Module UART -> MainBoard UART (requires header connectivity)

* Configuration
** With vendor software (requires Windows PC) - should be done before installing module into mower
** Over UART bus (only terminal) - should be done when RPI installed and operational

== Step-by step set-up guides ==
*[[Unicore GPS Setup-CAN| With wiring to mainboard and configuration on UART]]
* <TODO> add other guides

== Documentation ==
[https://core-electronics.com.au/attachments/localcontent/Unicore_Reference_Commands_Manual_For_N4_High_Precision_Products_V2_EN_R1_1_189543505cb.pdf Command reference]

== Software ==
The vendor offers [https://en.unicore.com/products/uprecise.html ''UPrecise''] to check all status details and configure the receiver. The UI is pleasing and has many features, but also quite some bugs. The download requires creating a free account.

== Configuration ==

=== Receiver ===
The following configuration works quite well. COM3 is used when connected via USB.<syntaxhighlight>
FRESET
CONFIG COM3 460800
MODE ROVER UAV
GPGGA 0.1
GPGSV 1
GPRMC 1
GPGSA 1
GPVTG 1
GPGST 1
SAVECONFIG
</syntaxhighlight>These lines can be pasted into ''UPrecise'' after connecting to the receiver. Theoretically, you can also connect directly to the receiver's TTY, but make sure to send CR+LF (<code>\r\n</code>) line endings, otherwise the commands won't be recognized.

=== OpenMower (<code>mower_config.txt</code>) ===
<syntaxhighlight lang="bash">
export OM_GPS_PROTOCOL="NMEA"
export OM_GPS_PORT="/dev/ttyUSB0"
export OM_GPS_BAUDRATE="460800"
</syntaxhighlight>

== Rebooting ==
Sometimes the receiver just can't get a fix. Then it might be helpful to reboot it. There are three buttons in ''UPrecise'', which execute these commands:
{| class="wikitable"
!Button
!Command
|-
|Hot Start
|<code>RESET</code>
|-
|Warm Start
|<code>RESET EPHEM</code>
|-
|Cold Start
|<code>RESET EPHEM ALMANAC IONUTC POSITION</code>
|}
See also section 8.3 ("Reset") in the [https://core-electronics.com.au/attachments/localcontent/Unicore_Reference_Commands_Manual_For_N4_High_Precision_Products_V2_EN_R1_1_189543505cb.pdf command reference]. In contrast to the <code>FRESET</code> command, these command '''don't''' wipe the configuration.