# Overview #

The USB2Serial debugging board allows you to watch the [serial port](https://github.com/mist-devel/mist-board/wiki/Troubleshooting#RS232) debug output of the ARM IO Controller. This is useful mainly for development and debugging, but may also help to trace problems.

![https://raw.githubusercontent.com/wiki/mist-devel/mist-board//serial_connected.jpg](https://raw.githubusercontent.com/wiki/mist-devel/mist-board/serial_connected.jpg)

The USB2Serial board connected to a V1.2 pre-production board.

**Note**
An alternative to this board is to get a USB to TTL cable [like this one](https://www.adafruit.com/product/954),
leaving the 5V pin unconnected but wiring TX to pin 4, RX to pin3, and ground to pin 1 (resp. white, green, black wires, with pin 1 being close to the edge).

# Schematic #

The board connects via SV3 to the ARM IO Controller debug connector of the MIST board V1.2 or V1.3.

![https://raw.githubusercontent.com/wiki/mist-devel/mist-board/usb2serial_schematic.png](https://raw.githubusercontent.com/wiki/mist-devel/mist-board/usb2serial_schematic.png)

[Schematic(PDF)](https://raw.githubusercontent.com/wiki/mist-devel/mist-board/usb2serial_schematic.pdf)

# Printed Circuit Board #

The board plugs directly into the MIST V1.2 or V1.3 (the first series board) board. Previous development boards came with rs232 transceivers and don't need this addon.

![https://raw.githubusercontent.com/wiki/mist-devel/mist-board/usb2serial_pcb.png](https://raw.githubusercontent.com/wiki/mist-devel/mist-board/usb2serial_pcb.png)

[Board(PDF)](https://raw.githubusercontent.com/wiki/mist-devel/mist-board/usb2serial_pcb.pdf)

# Debugging #

The communication parameters are 115200 bit/s 8N1.

![https://raw.githubusercontent.com/wiki/mist-devel/mist-board/serial_pcb.jpg](https://raw.githubusercontent.com/wiki/mist-devel/mist-board/serial_pcb.jpg)

An example debug output will look like this:

```
Minimig by Dennis van Weeren
ARM Controller by Jakub Bednarski

Version ATH130522

SDHC card detected
spiclk: 24 MHz
usb_init
max3421e_init()
Chip revision: 13
busprobe()
usb_reset_state
partition type: 0x72 (FAT16)
fat_size: 240
fat_number: 2
fat_start: 263
root_directory_start: 743
dir_entries: 512
data_start: 775
cluster_size: 32
cluster_mask: FFFFFFE0
file "CORE    RBF" found
FPGA bitstream file opened, file size = 367568
[***********************]
FPGA bitstream loaded
FPGA configured in 857 ms
Identified MiST core
Running mist setup
file "SYSTEM  FNT" not found
Uploading TOS ...
file "TOS     IMG" found
TOS.IMG:
  size = 196607
WARNING: Unexpected TOS size!
  blocks = 383
  address = $00fc0000
Uploading: [................................................]
TOS.IMG uploaded in 231 ms (851 kB/s / 6808 kBit/s)
Erasing cart memory
file "DISK_A  ST " found
A: eject
A: insert DISK_A  ST 
A: detected 2 sides with 9 sectors per track
file "DISK_B  ST " not found
file "HARDDISKHD " not found
=> CONDETIRQ
busprobe()
=> BUSEVENTIRQ
usb_configure(parent=0 port=0 lowspeed=0)
using free entry at 0
Setting addr 1
usb_set_addr(new=1)
usb_ctrl_req(addr=0, len=0, ptr=0x0)
trying to init class 0
usb_hub_init()
usb_ctrl_req(addr=1, len=8, ptr=0x20ff28)
usb_ctrl_req(addr=1, len=18, ptr=0x20ff28)
usb_ctrl_req(addr=1, len=8, ptr=0x20ff28)
usb_ctrl_req(addr=1, len=9, ptr=0x20ff28)
usb_ctrl_req(addr=1, len=0, ptr=0x0)
usb_ctrl_req(addr=1, len=0, ptr=0x0)
usb_ctrl_req(addr=1, len=0, ptr=0x0)
usb_ctrl_req(addr=1, len=0, ptr=0x0)
usb_ctrl_req(addr=1, len=0, ptr=0x0)
 -> accepted :-)
```