The Nintendo Switch mainboard has a series of testpads on the front and back, presumably used in factory test, diagnostics, and early board bringup procedures.

== Raw Logic captures ==

These are reference materials, taken from poking at I/O on various testpads. https://github.com/hedgeberg/Switch-Logic-Captures

== Photos ==

[[File:Switchre_side1.jpg|200px]]
[[File:Switchre_side2.jpg|200px]]

== Pinouts ==

=== Cluster A ===

{| class=wikitable
! Pad # || Name || Type || Levels || Continuity || Frequency || Comment
|-
| 1 || Batt GND? || || || || ||
|-
| 2 || Battery pulse? || Pulse train || 0-3.3V || L-5? || ||
|-
| 3 || Battery Vdd || || || || ||
|-
| 4 || Speaker R + || Square wave || 0-3.3V || || || Speaker Right +
|-
| 5 || Speaker R - || Square wave || 0-3.3V || || || Speaker Right -
|-
| 6 || Weak GND? || || || || ||
|-
| 7 || SDA || I2C || 0-1.8V || || ||
|-
| 8 || SCL || I2C || 0-1.8V || || ||
|-
| 9 || USB-PWR-WAVE? || Square wave || 0-3.3V || K-4, K-5? || ~11 Hz ||
|-
| 10 || USB-PWR-WAVE? || Square wave || 0-3.3V || K-4, K-5? || ~11 Hz ||
|}

=== Cluster B ===

{| class=wikitable
! Pad # || Name || Type || Levels || Continuity || Frequency || Comment
|-
| 1 || || DBVDD || || || || from ALC5639 pin 43
|-
| 2 || D+ || USB-C || || || || Cluster B - 3
|-
| 3 || D- || USB-C || || || || Cluster B - 2
|-
| 4 || +3.3V || XRST || || || || from M92T36 pin 4
|-
| 5 || +3.3V || VSVR || || || || from M92T36 pin 6
|-
| 5(b) || VUSB || VB || || || || from M92T36 pin 9
|-
| 6 || GND || || || || ||
|}

=== Cluster C ===

{| class=wikitable
! Pad # || Name || Type || Levels || Continuity || Frequency || Comment
|-
| 1 || ?? || || 0-1.8V || || || No clue. This is definitely important, we just have no idea how. May need to interface with dock for comms.
|-
| 2 || UART-A RX || || 0-1.8V || || || UART input
|-
| 3 || UART-A TX || || 0-1.8V || || || UART output
|-
| 4 || ?? || || 0-1.8V || || ||
|-
| 5 || ?? || || 0-1.8V || || ||
|-
| 6 || UART-A RTS || || 0-1.8V || || || UART-A Flow control
|-
| 7 || ?? || || 0-1.8V || || ||
|-
| 8 || UART-A CTS || || 0-1.8V || || || UART-A Flow control
|-
| 9 || ?? || || 0-1.8V || || ||
|-
| 10 || ?? || || 0-1.8V || || ||
|-
| 11 || +1.8V || || 0-1.8V || || ||
|}

=== Cluster D ===

{| class=wikitable
! Pad # || Name || Type || Levels || Continuity || Frequency || Comment
|-
| 1 || GND || || || || ||
|-
| 4 || Seaker L + || || || || || Speaker Left +
|-
| 5 || Seaker L - || || || || || Speaker Left -
|}

=== Cluster E ===

{| class=wikitable
! Pad # || Name || Type || Levels || Continuity || Frequency || Comment
|-
| 1 || Vol (-) || || || || || Button Vol (-)
|-
| 10 || Reset || || || || ||
|-
| 11 || Power Button || Pushbutton || 4V-0V || || || Active low
|}

=== Cluster G ===

{| class=wikitable
! Pad # || Name || Type || Levels || Continuity || Frequency || Comment
|-
| 2 || GND || || || || ||
|-
| 4 || Vol(+) || || || || || Button Vol (+)
|-
| 5 || Li-Ion Batt Vdd Mirror || || || || || Power Supply
|-
| 9 || BUTTON_HOME || || || || || RCM strap
|}

=== Cluster H ===

{| class=wikitable
! Pad # || Name || Type || Levels || Continuity || Frequency || Comment
|-
| 1 || || || || || ||
|-
| 2 || || || || || ||
|-
| 3 || || || || || ||
|-
| 4 || Screen_on || On/Off || 0-1.8v || I-2 || || Screen power state, active high
|-
| 5 || || Flow control || 0-1.8V || I-5 || Flow control for pad I-4? ||
|-
| 6 || || || || || ||
|-
| 7 || || UART || 0-1.8V || I-4 || 1.5MBaud?||
|-
| 8 || || UART || 0-1.8V || I-3 || 1.5MBaud?||
|-
| 9 || || || || || ||
|-
| 10 || || || || || H-12 || On the same trace
|-
| 11 || || || || || || Goes to a small ceramic cap near WiFi/BT IC?
|-
| 12 || || || || H-10 || || On the same trace
|}

=== Cluster I ===

{| class=wikitable
! Pad # || Name || Type || Levels || Continuity || Frequency || Comment
|-
| 1 || GND || || || || ||
|-
| 2 || Screen_on || On/Off || 0-1.8V || || || Screen power state, active high
|-
| 3 || || UART || 0-1.8V || || 1.5MBaud? ||
|-
| 4 || || UART || 0-1.8V || || 1.5MBaud? ||
|-
| 5 || || Flow control || 0-1.8V || || || Flow control for pad I-4?
|-
| 6 || || || 0-1.8V || || || Needs testing with chip/touch screen interface board plugged in
|}

=== Cluster J ===

{| class=wikitable
! Pad # || Name || Type || Levels || Continuity || Frequency || Comment
|-
| 1 || ? || Edge || 0-1.8V || || || Turns on around same time as pad J-3
|-
| 2 || GND || || || || ||
|-
| 3 || ? || Edge || 0-1.8V || || || Turns on around same time as pad J-1, slightly after
|-
| 4 || Power button || Pushbutton || 4V-0V || || || Active low
|-
| 5 || ? || Constant? || 0V || Ground?-NT || ||
|-
| 6 || ? || Edge || 0-1.8V || || || Turns on with pad J-6, ~1s after J-1/J-3
|-
| 7 || ? || Edge || 0-1.8V || || || Turns on with pad J-5, ~1s after J-1/J-3
|-
| 8 || ? || Edge? || 0-1.8V || || || Turns on ~1s after J-6/J-7, turns off at unknown point
|}

=== Cluster K ===

{| class=wikitable
! Pad # || Name || Type || Levels || Continuity || Frequency || Comment
|-
| 1 || GND || || || || ||
|-
| 2 || D- || USB-C || || || || Cluster B - 3
|-
| 3 || D+ || USB-C || || || || Cluster B - 2
|-
| 4 || USB-PWR-WAVE? || Square wave || 0V-3.3V || A-9, A-10? || ~11 Hz ||
|-
| 5 || USB-PWR-WAVE? || Square wave || 0V-3.3V || A-9, A-10? || ~11 Hz || Appears to mirror K4. Duty cycle 66.67%. Low on screen lock. Off until first interaction.
|-
| 6 || USB-C V+ || Supply power || || || || support fast charger : "normal mode = 5V+" "Fast changer = 12V+"
|-
| 7 || BQ24193 VBUS + M92T36 VEX || Power supply? || ~3V-0V || None known || N/A || 0 when usb-c not plugged in, falls slowly on first interaction if USB-C plugged in. Power draw related?
|}

=== Cluster L ===

TODO: Update diagram

{| class=wikitable
! Pad # || Name || Type || Levels || Continuity || Frequency || Comment
|-
| 1 || Li-Ion Batt Vdd Mirror || Power Supply || Std. Li-Ion || || ||
|-
| 2 || GND || || || || ||
|-
| 3 || Li-Ion Batt Vdd || Battery Input || Std. Li-Ion || || ||
|-
| 4 || Mirrored Ground? || || || || || Holds steady @ 0, looks like a decoupled isolated ground
|-
| 5 || Battery pulse? || || || || <1 Hz || Duty cycle ~0%
|-
| 6 || GND || || || || ||
|}