Update README.md

README.md

@@ -15,8 +15,7 @@
 | ----------------------------------------- | ---------------------------------------- | ------------------------------------ |
 | ![front](https://i.imgur.com/OyAF7rm.jpg) | ![back](https://i.imgur.com/2qvz6Kv.jpg) | ![](https://i.imgur.com/r5hJnPY.jpg) |
 
-> `Rev 3.X` is designed to be used with [ErgoSNM `Rev 2.X`](https://github.com/ziteh/ergo-snm-keyboard/releases/tag/v2.0.0).  
-> If you want ***2.54mm pin header*** instead of FPC connector, please refer to [`Rev 2.1`](https://github.com/ziteh/pmw3360-pcb/releases/tag/v2.1.0).
+🚩**NOTE**: `Rev 3.X` is designed to be used with [ErgoSNM](https://github.com/ziteh/ergo-snm-keyboard/releases/tag/v2.0.0), if you prefer ***2.54mm pin header*** instead of FPC connector, please refer to [`Rev 2.1`](https://github.com/ziteh/pmw3360-pcb/releases/tag/v2.1.0).
 
 - V_IN range: 2.0\~5.5V. Must be same or greater then V_DD+0.2V, depends on LDO specs and JP1 config.
 - V_DD (i.e. VDD of PMW3360) range: 1.8\~2.1V, Typ. 1.9V.
@@ -40,18 +39,26 @@ If you want it to work with a 3.3V MCU, then connect V_IN to 3.3V, and connect `
 | U1     | PMW3360DM-T2QU  | PMW3360DM-T2QU 16 Pin  |
 | U2\*   | TPS73601DBV     | SOT-23-5               |
 | J1     | 0.5mm FPC 8P    | AFC01-S08FCA-00        |
-| JP1    | Solder Jumper   | 1.0*1.5mm              |
 
 - Adjust the V_DD voltage with the value of R4 and R5.
   - For 1.8V V_DD, *Adj_R1*=28.0kΩ and *Adj_R2*=56.2kΩ.
 - U2 LDO can be replace by RT9193-18GB, just change C3 and C4 to 1uF, change R5 to a 22nF or larger ceramic capacitor, and R4 don't install.
-- R3 is additional nRESET pull up resistor. Because nRESET pin of PMW3360 has a built in weak pull up circuit, so R3 is optional.
+- R3 is optional/additional nRESET pull up resistor, nRESET pin of PMW3360 has a built in weak pull up circuit.
 
 ## Jumper Config
 
 - JP1: V_IO voltage selection
-  - \[1-2 3\]: V_IO=V_IN
-  - \[1 2-3\]: V_IO=V_DD
+  - 1 and 2 ON (close): V_IO = V_IN
+  - 3 and 2 ON (close): V_IO = V_DD
+
+## PCB Characteristics
+- Copper layer count: 2
+- Board overall dimensions: 27 mm x 28 mm
+- Min track/spacing: 0.2 mm / 0.2 mm
+- Min hole diameter: 0.3 mm
+- Castellated pads: No
+- Plated board edge: No
+- Edge card connectors: No
 
 ## Firmware