Pin table for Nucleo-401 added to main readme

Author: Dajamante

README.md

@@ -20,6 +20,8 @@ The NBMC appears to the main Neotron system processor as an Expansion Device. As
 
 ## Hardware Interface
 
+### Neotron Pico
+
 The NBMC firmware is designed to run on an ST Micro STM32F0 (STM32F031K6T6) microcontroller
 
 * 32-bit Arm Cortex-M0+ Core
@@ -71,6 +73,44 @@ This design should also be pin-compatible with the following SoCs (although this
 
 Note that not all STM32 pins are 5V-tolerant, and the PS/2 protocol is a 5V open-collector system, so ensure that whichever part you pick has 5V-tolerant pins (marked `FT` or `FTt` in the datasheet) for the PS/2 signals. All of the parts above _should_ be OK, but they haven't been tested. Let us know if you try one!
 
+### Nucleo-F401
+
+The NBMC firmware is originally designed to run on an ST Micro STM32F0 (STM32F031K6T6) microcontroller. This MCU has:
+
+* 32-bit Arm Cortex-M4 Core
+* 3.3V I/O (5V tolerant)
+* 512 KBytes Flash
+* 96 KBytes SRAM
+* LQFP64 package (10 * 10 mm)
+
+| CPU Pin | Nucleo-64 Pin | Name | Signal      | Function                                  |
+| ------- | ------------- | ---- | ----------- | ----------------------------------------- |
+| 2       | CN7 23        | PC13 | BUTTON_nPWR | Power Button Input (active low)           |
+| 33      | CN10 16       | PB12 | BUTTON_nRST | Reset Button Input (active low)           |
+| 34      | CN10 30       | PB13 | MON_3V3     | 3.3V rail monitor Input (1.65V nominal)   |
+| 35      | CN10 28       | PB14 | MON_5V      | 5.0V rail monitor Input (1.65V nominal)   |
+| 36      | CN10 26       | PB15 | nSYS_RESET  | System Reset Output (active low)          |
+| 8       | CN8 6         | PC0  | DC_ON       | PSU Enable Output (active high)           |
+| 20      | CN8 3         | PA4  | SPI1_NSS    | SPI Chip Select Input (active low)  ??    |
+| 21      | CN5 6         | PA5  | SPI1_SCK    | SPI Clock Input                           |
+| 22      | CN5 5         | PA6  | SPI1_MISO   | SPI Data Output                           |
+| 23      | CN5 4         | PA7  | SPI1_MOSI   | SPI Data Input                            |
+| 9       | CN6 5         | PC1  | POWER_LED   | Output for Power LED                      |
+| 10      | CN7 35        | PC2  | STATUS_LED  | Output for Status LED                     |
+| 11      | CN7 37        | PC3  | IRQ_nHOST   | Interrupt Output to the Host (active low) |
+| 42      | CN10 21       | PA9  | USART1_TX   | UART Transmit Output                      |
+| 43      | CN10 33       | PA10 | USART1_RX   | UART Receive Input                        |
+| 44      | CN10 14       | PA11 | USART1_CTS  | UART Clear-to-Send Output                 |
+| 45      | CN10 12       | PA12 | USART1_RTS  | UART Ready-to-Receive Input               |
+| 46      | CN7 13        | PA13 | SWDIO       | SWD Progamming Data Input                 |
+| 49      | CN7 15        | PA14 | SWCLK       | SWD Programming Clock Input               |
+| 25      | CN10 6        | PC5  | PS2_CLK0    | Keyboard Clock Input                      |
+| 26      | CN8 4         | PB0  | PS2_CLK1    | Mouse Clock Input                         |
+| 27      | CN10 24       | PB1  | PS2_DAT0    | Keyboard Data Input                       |
+| 28      | CN10 22       | PB2  | PS2_DAT1    | Mouse Data Input                          |
+| 58      | CN10 17       | PB6  | I2C1_SCL    | I²C Clock                                 |
+| 59      | CN7 21        | PB7  | I2C1_SDA    | I²C Data                                  |
+
 ## SPI Communications Protocol
 
 The SPI interface runs in SPI mode 0 (clock line idles low, data sampled on rising edge) at up to 16 MHz (TBD). It uses frames made up of 8-bit words.