lpc55xx_hic: Add documentation for MCU-LINK and MCU-LINK-PRO support

Author: mbrossard

docs/hic/lpc55xx.md

@@ -31,17 +31,60 @@ Reference design is based on [MCU-Link](https://www.nxp.com/design/development-b
 | SWDIO / TMS | I/O | PIO0_2  |  52 |
 | SWO / TDO   |  I  | PIO0_3  |  53 |
 | TDI         |  O  | PIO0_1  |   2 |
-| nRESET      |  O  | PIO0_19 |  58 |
+| nRESET      | I/O | PIO0_19 |  58 |
 | GNDDetect   |  I  | PIO0_22 |  50 |
 | UART        |
 | UART RX     |  I  | PIO0_24 |  45 |
 | UART TX     |  O  | PIO0_25 |  51 |
-| Button      |
-| NF-RST But. |  I  | PIO0_18 |  38 |
-| F-RST  But. |  I  | PIO1_27 |  18 |
 | LEDs        |
 | Con. LED    |  O  | PIO0_5  |  56 |
 
 Additional pins are used to drive external circuitry:
 - SWDIO TX Enable (PIO0_28, pin 44)
 - nRESET Output Enable (PIO0_13, pin 46)
+
+## MCU-LINK and MCU-LINK-PRO support
+
+The `lpc55s69_mculink_bl` and `lpc55s69_mculink_if` images support both
+MCU-LINK and MCU-LINK-PRO boards. Installation of the bootloader can be
+done by putting the board in firmware update mode and using the NXP
+`blhost` tool:
+
+```
+$ blhost --usb 0x1fc9,0x0021 flash-image lpc55s69_mculink_bl_crc.hex erase
+```
+
+### MCU-LINK "Buttoms"
+
+The MCU-LINK does not have amy buttons, but both board have "Disable VCOM"
+and "Disable SWD" respectively mapped to non-forwarding reset and
+forwarding reset functionality in DAPLink.
+
+| Signal      | I/O | Symbol  | Pin |
+|-------------|:---:|---------|:---:|
+| Button      |
+| NF-RST But. |  I  | PIO0_18 |  38 |
+| F-RST  But. |  I  | PIO0_27 |  18 |
+
+### MCU-LINK-PRO detection and LEDs
+
+The [MCU-LINK-PRO](https://www.nxp.com/design/microcontrollers-developer-resources/mcu-link-pro-debug-probe:MCU-LINK-PRO)
+defines board type detection using `HW_VER_4` and `HW_VER_3`. When
+`HW_VER_4` and `HW_VER_3` are respectively low and high, we determine that
+the board is a MCU-LINK-PRO, otherwise we assume the board is a MCU-LINK.
+MCU-LINK only has one red activity LED. MCU-LINK-PRO has 7 LEDs (1 red
+and 6 green), 5 are currently used by DAPLink (see table below).
+
+| Signal        | I/O | Symbol  |
+|---------------|:---:|---------|
+| Detection     |
+| HW_VER_4      |  I  | PIO1_5  |
+| HW_VER_3      |  I  | PIO1_4  |
+| LEDs          |
+| Con. LED  (r) |  O  | PIO0_5  |
+| Run. LED  (g) |  O  | PIO1_17 |
+| HID LED   (g) |  O  | PIO1_13 |
+| CDC LED   (g) |  O  | PIO1_18 |
+| MSC LED   (g) |  O  | PIO1_15 |
+| N/A LED 1 (g) |  O  | PIO1_12 |
+| N/A LED 2 (g) |  O  | PIO1_12 |