nrf52840_hic: Add documentation for nrf52840 HIC

docs/hic/README.md

@@ -20,5 +20,6 @@ Support for these HICs has been recently added.
 
 | HIC                           | Core |  Freq.  |  RAM   |  ROM   | USB |
 |-------------------------------|:----:|--------:|-------:|-------:|:---:|
+| [nrf52840](nrf52840.md)       |  M4  |  64 MHz |  64 KB | 256 KB |  FS |
 | [stm32f072x8](stm32f072xx.md) |  M0  |  48 Mhz |  16 KB |  64 KB |  FS |
 | [stm32f072xb](stm32f072xx.md) |  M0  |  48 Mhz |  16 KB | 128 KB |  FS |

docs/hic/nrf52840.md

@@ -0,0 +1,40 @@
+# nrf52840 HIC
+
+Based on Nordic [nRF52840](https://www.nordicsemi.com/Products/nRF52840):
+- Cortex-M4 64 MHz
+- 1MB Flash (limited to 256 KB)
+- 64 KB RAM
+- Full-speed USB 2.0 device controller: up to 9 bi-directional endpoints including EP0 (*)
+- aQFN73 or QFN48 packaging
+
+(*) "Endpoints: 2 control (1 IN, 1 OUT) [...] 14 bulk/interrupt (7 IN, 7 OUT) [...] 2 isochronous (1 IN, 1 OUT)" (source: [Datasheet](https://infocenter.nordicsemi.com/pdf/nRF52840_PS_v1.7.pdf))
+
+## Memory Map
+
+| Region   |  Size  | Start       | End         |
+|----------|--------|-------------|-------------|
+| Flash    | 256 KB | 0x0000_0000 | 0x0004_0000 |
+| SRAM     |  64 KB | 0x2000_0000 | 0x2001_0000 |
+
+Bootloader size is 64 KB
+
+## DAPLink default pin assignment
+
+| Signal      | I/O | Symbol  | Pin |
+|-------------|:---:|---------|:---:|
+| SWD         |
+| SWCLK       |  O  | P0.13   |     |
+| SWDIO       | I/O | P0.17   |     |
+| nRST        |  O  | P0.09   |     |
+| UART        |
+| UART TX     |  I  | P0.24   |     |
+| UART RX     |  O  | P1.00   |     |
+| Button      |
+| F-RST  But. |  I  | P1.06   |     |
+| LEDs        |
+| HID LED     |  O  | P0.06   |     |
+| MSD LED     |  O  | P0.08   |     |
+| CDC LED     |  O  | P0.12   |     |
+
+Note:
+- LEDs have active state low.