[UNVERIFIED] Astra diagram pass

Architecture/IO_ARCHITECTURE.md

@@ -68,13 +68,14 @@ external analogue-pin pool, so they increase concurrent conversion capacity
 rather than doubling the number of physical sensor pins. The proposed V1
 allocation occupies 16 conditioned ADC channels:
 
-```text
-4 thermistor inputs
-9 general 0-5 V inputs
-1 VBAT_PROT sense input
-1 +5V_SENS sense input
-1 +12V_SENS sense input
-```
+| Conditioned ADC input class | Channels |
+| --- | ---: |
+| Thermistors | 4 |
+| General 0–5 V inputs | 9 |
+| `VBAT_PROT` sense | 1 |
+| `+5V_SENS` sense | 1 |
+| `+12V_SENS` sense | 1 |
+| **Total** | **16** |
 
 This leaves meaningful MCU ADC and pin margin, but the final STM32 package and
 pin assignment must reserve all analogue pins alongside timer, CAN, debug,
@@ -90,11 +91,7 @@ because an open thermistor drives the node towards 5 V. Firmware calculates the
 thermistor resistance from the ratio of its ADC result to the `+5V_SENS` ADC
 result, then applies the calibration map for the selected sensor.
 
-```text
-+5V_SENS -- precision pull-up --+-- thermistor -- sensor ground
-                                 |
-                              attenuation/filter --> ADC
-```
+![Thermistor](diagrams/thermistor.svg)
 
 The pull-up value is selected from the actual NTC curve and required
 temperature range, balancing resolution against self-heating. The attenuation
@@ -169,13 +166,9 @@ released. It has two independent destinations:
 - `DEADMAN_OK` is combined in hardware with the MCU's `MCU_RUN_PERMIT` output
   to produce `ENGINE_PERMIT`.
 
-```text
-deadman contact A --> protected input --> DEADMAN_A_HELD --------+
-                                                                  +--> valid-state logic --> DEADMAN_OK --+
-deadman contact B --> protected input --> inverted --> DEADMAN_B_RELEASED -+                              |
-                                                                                                            AND --> ENGINE_PERMIT
-MCU_RUN_PERMIT ----------------------------------------------------------------------------------------------+
-```
+![Deadman inputs](diagrams/deadman-inputs.svg)
+
+![Deadman permit](diagrams/deadman-permit.svg)
 
 `ENGINE_PERMIT` controls the enable inputs of the injector and ignition drivers
 where those inputs are provided. If a selected driver has no suitable enable
@@ -239,9 +232,7 @@ only when the selected external starter switch accepts that interface.
 Analogue output is not a V1 functional requirement. Reserve two MCU pins and
 board footprints for future 0-5 V outputs. The intended future path is:
 
-```text
-DAC --> rail-to-rail buffer --> protection / series impedance --> connector
-```
+![Dac output](diagrams/dac-output.svg)
 
 A true calibrated 0-5 V output may require an external 5 V-referenced DAC or
 a suitably characterised buffer stage. A general 0-12 V analogue output is not