diff --git a/README.md b/README.md
index 1815a48..9d95a35 100644
--- a/README.md
+++ b/README.md
@@ -15,7 +15,8 @@ yet tear-free.
 ## Hardware
 
 - ESP-WROOM-32 dev board (`esp32dev`)
-- Planar EL512.256-H, configured for **two-bit parallel mode** (mode jumper OFF, see datasheet)
+- Planar EL512.256-H, configured for **two-bit parallel mode**: jumper 2 (DCONFIG) of pin
+  strip PS1 removed, jumper 1 (SELFTST) fitted (datasheet Table 3)
 - Datasheet: [docs/datasheet/EL512.256-H3 FRB.pdf](docs/datasheet/EL512.256-H3%20FRB.pdf)
 - Check the panel's logic-level and supply requirements in the datasheet before wiring.
 
@@ -36,12 +37,18 @@ The pin map lives in [include/pins.h](include/pins.h).
 
 ## Timing
 
-| Parameter            | Value                                   |
-|----------------------|-----------------------------------------|
-| Pixel clock (VCLK)   | 5 MHz, 2 pixels per clock               |
-| Clocks per row       | 272 (256 data + 16 blanking)            |
-| Lines per frame      | 261 (256 visible + 5 blanking)          |
-| Refresh              | 5 MHz / (272 × 261) ≈ 70.4 Hz           |
+| Parameter            | Value                                   | Datasheet limit (Tables 5, 6)   |
+|----------------------|-----------------------------------------|---------------------------------|
+| Pixel clock (VCLK)   | 5 MHz, 2 pixels per clock               | 30 MHz max, keep running        |
+| HS high (T7)         | 256 clocks                              | 256 in two-bit mode, even       |
+| HS low (T6)          | 16 clocks                               | 4 clocks min                    |
+| HS period (T8)       | 272 clocks = 54.4 µs                    | 50 µs min                       |
+| Lines per frame      | 261 (256 visible + 5 blanking)          | 256 rows + T1                   |
+| Front porch (T1)     | 220.8 µs (last row end to VS rise)      | 100 µs min                      |
+| Refresh              | 5 MHz / (272 × 261) ≈ 70.4 Hz           | 70 Hz typ, 75 Hz max            |
+
+The datasheet ([docs/datasheet/](docs/datasheet/EL512.256-H3%20FRB.pdf)) is the source of
+truth; if anything here disagrees with it, the datasheet wins.
 
 ## Layout
 
diff --git a/docs/README.md b/docs/README.md
index 4f891b0..a9976d0 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -29,12 +29,23 @@ I2S0 setup (`EL512Panel::startI2S()`), following bitluni's ESP32Lib 8-bit mode:
 
 ## From the datasheet
 
-- Two-bit parallel mode is selected with the mode jumper OFF. Even columns on VID,
-  odd columns on TVID; 256 VCLKs per row.
+The datasheet is the source of truth for everything in this section and wins over any
+other doc, comment or the plan.
+
+- Two-bit parallel mode is selected by removing jumper 2 (DCONFIG) of pin strip PS1
+  (Table 3; factory default has jumpers 1 and 2 fitted). Even columns on VID, odd
+  columns on TVID, numbered from the left as seen by the viewer; 256 VCLKs per row.
 - VCLK is active on the rising edge and should be kept running.
-- HS is high while the pixels of a row are clocked in. The number of VCLKs during HS
-  high should be even.
-- The topmost row is the first HS high time ending after the rising edge of VS.
+- HS envelopes the pixels of a row: the visible pixels are the last 512 (two-bit mode:
+  last 256 clocks) before HS falls. The number of VCLKs during HS high should be even.
+- The topmost row is the first HS high time ending after the rising edge of VS. Only
+  the rising edge of VS is used; VS high/low time is at least 1 VCLK (T2).
+- Table 5: front porch T1 >= 100 µs, HS setup to VS T4 >= 1 VCLK, HS hold from VS
+  T5 >= 3 µs, HS low T6 >= 4 VCLK, HS period T8 >= 50 µs, VS 70 Hz typ / 75 Hz max.
+- Figure 4 / Table 6: VID, TVID, HS and VS need 8 ns setup and 8 ns hold around the
+  rising VCLK edge; VCLK period >= 33 ns (30 MHz max).
+- Inputs are HCT compatible with pull-ups (Table 4: high >= 2 V, low <= 0.8 V,
+  abs. max Vcc1 + 0.5 V). ENABLE and _LOWPWR are on J2 and pulled high internally.
 
 ## Open items
 
diff --git a/lib/EL512/src/EL512Panel.h b/lib/EL512/src/EL512Panel.h
index cceab2e..189f1e5 100644
--- a/lib/EL512/src/EL512Panel.h
+++ b/lib/EL512/src/EL512Panel.h
@@ -10,7 +10,7 @@
 //   byte bit 3 = VS    (marks the top row)
 //   I2S BCK   -> VCLK  (panel samples data on the rising edge)
 //
-// Panel in two-bit parallel mode (jumper OFF, see datasheet), 5 MHz VCLK:
+// Panel in two-bit parallel mode (PS1 jumper 2 removed, datasheet Table 3), 5 MHz VCLK:
 //   272 clocks per row (256 data + 16 blanking), 261 rows per frame
 //   (256 visible + 5 blanking) -> 5e6 / (272 * 261) ~= 70.4 Hz.
 //