diff --git a/content/posts/rmk-ferris-sweep/index.md b/content/posts/rmk-ferris-sweep/index.md
index 9637534..b8c81ee 100644
--- a/content/posts/rmk-ferris-sweep/index.md
+++ b/content/posts/rmk-ferris-sweep/index.md
@@ -47,4 +47,20 @@ My [keymap](https://github.com/gabevenberg/qmk_firmware/blob/personal/keyboards/
 is a bit complex, so it took some time to port.
 It was mostly tedium rather than anything truly headscratching, however.
 
+Next, and the most complicated step, was creating a `vial.json`.
+The json file [provided by the via project](https://github.com/the-via/keyboards/blob/master/src/ferris/sweep/sweep.json) was wrong,
+as it layed out the keyboard as a 8x5, rather than a 4x10 that I had done in rmk.
+So I had to take that file, load it into the [keyboard layout editor](https://www.keyboard-layout-editor.com/),
+and follow [vials guide](https://get.vial.today/docs/porting-to-via.html) to remake the `vial.json` in the right layout.
+
+Finally, I could flash my keyboard.
+I flashed it, and... It didnt work.
+The left hand side, the one plugged into USB, worked fine, all keys worked.
+But the right hand side, connected to the main by TRRS, did nothing.
+A day or 2 of investigation later revealed that the half-duplex serial implementation
+only used the RP2040s internal pull-up resistors, which for my keyboard and TRRS cable,
+were insufficient for a baud rate of 115200.
+This was (temporarily) fixed by setting a lower baud rate,
+but for the long term, ive made a PR mirroring [QMKs solution](https://github.com/qmk/qmk_firmware/blob/6d0e5728aa61b442885d48caf49d29e5c60e8197/platforms/chibios/drivers/vendor/RP/RP2040/serial_vendor.c#L133) to this problem.
+
 The final file looked like [this](https://github.com/gabevenberg/ferris-sweep-rmk/blob/main/keyboard.toml)