Preliminary Documentation for SA series builds.

content/en/docs/contributions/sa-series-notes/_index.md

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+---
+title: "Notes on building an SA900ECO"
+linkTitle: "SA900ECO Build"
+weight: 100
+description: >-
+     This includes some notes on building an SA900ECO with the 0.13 mainboard from Vermut's shop.
+---
+
+## YardForce SAxxxECO series notes
+
+(as of 3rd June 2024)
+
+Here are my findings for an SA900ECO build but the findings may also be useful for other SAxxxECO models which look very similar:
+
+### Robot build Notes:
+- Generally you can follow the steps for the Classic 500 build using Vermut 0.13x kit, it is broadly similar. https://openmower.de/docs/robot-assembly/assemble-the-robot/photo-guide/
+- After opening up the mower you can remove the front wire detector bar and put aside for now. Not needed for the current build as of Jun '24.
+- One way to mount the SimpleRTK antenna is to bolt the square green GPS antenna shield board on top of the mower at the front, and run the cable inside the (now-removed) wire detector bar gromet at the front of the main housing.
+- The charging cable connector on the new vermut board is a bit weak (can snap off easily), and also the existing cable from the outer housing charging pins to the inner board was a bit short, so this connector snapped off on mine.  It is probably worth upfront either putting an extension on the charging cable or solder some wires to the board in place of the rigid connector that is there, with the connectors of your choice in order to extend the charging cable. I soldered a short 15cm cable onto the board with XT connectors to the charging pin cable to allow a bit more room when removing the cover for maintenance.
+- The SA900 has x4 hall sensors for the x4 wheels, compared to just x2 for the YF 500 Classic I believe.  There are x4 Hall sensor sockets on the 0.13 version mainboard (x2 for the front wheels and x2 for the emergency stop button).  However (personal choice) I plugged all four wheels into the x4 hall sensors sockets on the mainboard.  More details in pico firmware section below.
+- My recommendation is to put a 4A slow fuse in the inside of the two fuse sockets (Maybe a fast-blow is better but just copying what @ow did )
+- When closing the mower up again make sure the cables underneath are tight and tidy and wont get cut by mower blades!
+
+### Docking station / charger build
+- When modifying the charger , it is largely similar but slightly different to the YF Classic 500 one, and you will need some flush cutters to hack out a small bit of plastic when you come to close it up again. You will see.  It’s not problem.
+
+
+### Mainboard Pico firmware:
+- The hall sensors on the SA900ECO work the opposite way round to on the Yardforce classic.  So you will need to edit the firmare and invert the pin readings.  This is best done in VSCode with platformIO plugin.  First you need to edit the main Firmware/LowLevel/main.cpp file in the OpenMower repo to invert the hall sensors logic (remove the "!"'s) leaving the below:
+```
+    uint8_t emergency_read =  gpio_get(PIN_EMERGENCY_3) << 1 | // Stop1
+                              gpio_get(PIN_EMERGENCY_4) << 2 | // Stop2
+                              gpio_get(PIN_EMERGENCY_1) << 3 | // Lift1
+                              gpio_get(PIN_EMERGENCY_2) << 4 | // Lift2
+```
+If like me you have connected all wheel hall sensors to the x4 sockets on the mainboard, then the Emergency STOP button isn't used, and pins 3&4 instead become two more lift sensors.
+
+To handle this, firstly you need to change datatypes.h to take the stop button out of action and add x2 more lift sensors:
+```
+#define LL_EMERGENCY_BIT_LIFT1 LL_EMERGENCY_BIT_HALL1
+#define LL_EMERGENCY_BIT_LIFT2 LL_EMERGENCY_BIT_HALL2
+#define LL_EMERGENCY_BIT_LIFT3 LL_EMERGENCY_BIT_HALL3
+#define LL_EMERGENCY_BIT_LIFT4 LL_EMERGENCY_BIT_HALL4
+#define LL_EMERGENCY_BITS_LIFT (LL_EMERGENCY_BIT_LIFT1 | LL_EMERGENCY_BIT_LIFT2 | LL_EMERGENCY_BIT_LIFT3 | LL_EMERGENCY_BIT_LIFT4)
+#define LL_EMERGENCY_BITS_STOP 0b01000000 // placeholder for SA900ECO config - this is wrong and this bit can never be achieved.
+```
+and then back in main.cpp change the lift logic to something akin to:
+```
+// Handle lifted (both wheels are lifted)
+    // Calculate the number of lift emergency bits set
+    int8_t bitsSetCount = 0; 
+    for(int i = 0; i < 8; i++){
+        bitsSetCount += ((emergency_read & LL_EMERGENCY_BITS_LIFT) >> i) & 0x01;
+    }
+
+    if (bitsSetCount > 1) {
+        // If we just lifted (more than one wheel), store the timestamp
+        if (lift_emergency_started == 0) {
+            lift_emergency_started = millis();
+        }
+    } else {
+        // Not lifted, reset the time
+        lift_emergency_started = 0;
+    }
+```
+
+Then build with platformIO and copy new firmware.elf onto RasPi4 and flash onto PICO with './upload_firmware.sh firmware.elf'.
+
+
+### ESC's
+
+- Download VESCtool and learn to connect to the x3 ESCs and upload the write XML config file onto each ESC for the SA650ECO (which is broadly similar).  I have set my mow motor max rpms to 12500 I think, FYI.  https://github.com/ClemensElflein/OpenMower/tree/main/configs/xESC
+
+
+### UI
+In the above build there are no functional buttons on the mower itself... everything needs doing in the mower web interfaces, or you can set up your own UI using HomeAssistant or NodeRed for example.