add more errata

README.md

@@ -88,6 +88,22 @@ Errata for V1.0
    - We could use RT7272, which has an adjustable current limit. That way, we can use a
      smaller inductor but we will have less current available for external circuits (i.e.
      adjust the fuses, as well).
+4. DCDC could support more current.
+   - It was supposed to deliver up to 1.5 A but it only does that up to 20V of input voltage.
+   - It can deliver 1 A until 29V of input voltage.
+   - It would be good to have 1.5 A with a bit over 30V of input voltage.
+   - If you try to draw more current, it will go into shutdown regularly. It gets rather hot
+     so we assume that this is over-temp shutdown.
+   - The test was with the bare board so it might be a bit better when it is connected to the
+     main board. However, it will be in a closed case and the 3.3V LDO will generate additional
+     heat so it might be even less.
+   - Fix: Use a different DCDC (e.g. RT7272 with synchronous rectifier), add more thermal vias
+     (especially for the diode), maybe thermally decouple the diode from the DCDC IC.
+5. Buzzer could be louder.
+   - Remove the 2k resistor because it isn't needed. That doesn't make much of a difference
+     so we actually keep it for this batch. The difference is barely noticable when bridging
+     it with a jumper wire.
+   - Somehow make it louder, e.g. choose a different one or connect it to 5V.
 
 ### Hotfix would be useful
 
@@ -113,6 +129,22 @@ Errata for V1.0
     ground offset. We would expect something like 0.5V, which is still in the spec. If we
     have an offset of 1V, we will send 19 mA through the ESD diodes (limited by the series
     resistor), which isn't great but should be harmless.
+2. Silk text for SWD connector is swapped.
+  - **Hotfix**: At correct pinout with a sticker.
+
+### Hotfix is necessary to avoid degraded function
+
+1. I2C pins for displays are swapped in schematic.
+  - I did look through the symbol and footprint several times to not get this wrong. Oh, well...
+  - **Hotfix**: Add some kapton tape between OLED PCB and our display PCB to isolate SCL and SDA.
+    Only connect GND and 3.3V in the planned way. I2C signals can be connected to the test points
+    with some fixup wires.
+2. CJ2301 and AO3004 have high input capacity. That seems to break the voltage converter
+   for WS2812.
+  - It worked on all boards in the initial test (no DCDC, supplied by USB) but EMI from
+    the DCDC seems to be enough to break it on most boards.
+  - **Hotfix**: Replace by BSS138. They are a known-good choice and fxk8y has some at hand.
+  - Fix is needed for Q7 but it would also be useful for Q3 and Q4.
 
 ### Planned changes before deploying the boards
 
@@ -125,6 +157,18 @@ Errata for V1.0
 - Bend F3 upwards (and a bit to the left) to have more space for wires at J1.
 - Add "Anschlussplan".
 
+### Errors by JLC
+
+- 7 of 30 main boards had soldering errors at the TMP102. Most of them were breaking the
+  I2C but one had a short between 3.3V and GND. Fixed by unsoldering with hot air, clean,
+  solder again.
+- 4-5 display boards had one or more errors in the WS2812 ring. Mark first LED that doesn't
+  light up, heat solder joints of surrounding LEDs, test again. Repeat until whole ring is
+  fixed.
+- TMP102 also doesn't work on some display boards. Exact count is t.b.d.
+- Text for test points on main PCB is missing although some smaller text is present.
+  - t.b.d. whether this is an error in the Gerber data or at JLC
+
 
 Next Steps
 ----------