# USB PD chip evaluation configuration

This board configuration implements a USB Power Delivery TCPM in order to
evaluate various TCPC chips. The code tries to follow the preliminary USB PD
interface standard but for TCPC chip implementing proprietary I2C protocol, a
new TCPM file can be implemented as explained in the
[Updating the code](#Updating-the-code) section below.

## Building

### Chromium OS chroot

All the following instructions have been verified in a ChromiumOS chroot. You
can find how to set one up on the Chromium development:
[http://dev.chromium.org/chromium-os/quick-start-guide](http://dev.chromium.org/chromium-os/quick-start-guide)

### Build the TCPM code

`cd src/platform/ec`

`make BOARD=pdeval-stm32f072`

## Updating the code

### TCPC Communication code

Please duplicate [driver/tcpm/tcpci.c](../../driver/tcpm/tcpci.c) into
**driver/tcpm/##chip#name##.c**. Then update the control logic through I2C
there.

In order for your new code to compile, you need to update
[driver/build.mk](../../driver/build.mk) with the new file :
`driver-$(CONFIG_USB_PD_TCPM_##CHIP#NAME##)+=tcpm/##chip#name##.o` then document
the new `CONFIG_USB_PD_TCPM_` variable in the
[include/config.h](../../include/config.h) file and define it in the board
configuration in [board/pdeval-stm32f072/board.h](board.h).

### Board configuration

In [board/pdeval-stm32f072/board.h](board.h), you can update
`CONFIG_USB_PD_PORT_MAX_COUNT` to the actual number of ports on your board. You
also need to create/delete the corresponding `PD_Cx` tasks in
[board/pdeval-stm32f072/ec.tasklist](ec.tasklist).

By default, the firmware is using I2C1 with SCL/SDA on pins PB6 and PB7, running
with a 100kHz clock, and tries to talk to TCPCs at i2c slave addresses 0x9c and
0x9e. To change the pins or speed, you need to edit `i2c_ports` in
[board/pdeval-stm32f072/board.c](board.c), update `I2C_PORT_TCPC` in
[board/pdeval-stm32f072/board.h](board.h) with the right controller number, and
change the pin mux in [board/pdeval-stm32f072/gpio.inc](gpio.inc). To change
TCPC i2c slave addresses, update `TCPC1_I2C_ADDR` and `TCPC2_I2C_ADDR` in
[board/pdeval-stm32f072/board.h](board.h).

The I2C bus needs pull-up resistors on SCL/SDA. If your setup doesn't have
external pull-ups on those lines, you can activate the chip internal pull-ups
(but they are a bit weak for I2C) by editing
[board/pdeval-stm32f072/gpio.inc](gpio.inc) and updating the alternate mode
configuration flags with `GPIO_PULL_UP` e.g. : `ALTERNATE(PIN_MASK(B, 0x00c0),
1, MODULE_I2C, GPIO_PULL_UP) /* I2C MASTER:PB6/7 */`

An interrupt line, PA1, is configured to be used for the TCPC to get the
attention of the TCPM. The GPIO is configured to trigger an interrupt on the
falling edge and will call `tcpc_alert()`, which must be implemented in
**driver/tcpm/<vendor>.c**, and should determine the cause of the interrupt and
take action. The GPIO can be changed in
[board/pdeval-stm32f072/gpio.inc](gpio.inc).

## Flashing and Running

### Flashing the firmware binary

To flash through JTAG with OpenOCD, you can just run:

`sudo make flash BOARD=pdeval-stm32f072`

Note: you need to do that with your USB mini-B cable is connected to the **USB
ST-LINK** plug on the discovery board.

### Connecting to the firmware console

Connect a USB cable to the **USB USER** mini-B receptacle on the board. `lsusb`
should show you a device with the following ID : 18d1:500f

You can get a console over USB by issuing the following command on a Linux
computer:

`echo '18d1 500f' | sudo tee /sys/bus/usb-serial/drivers/generic/new_id`

## Testing

Currently, the TCPM is expecting to have a GPIO to detect VBUS, but to minimize
the HW setup with the discovery board the alternative is to fake VBUS detection
using either the **USER** button on the discovery board, or the `vbus` console
command, both of which toggle the state of VBUS detected. For example, to make
get a PD contract with a power adapter, plug in the adapter and then toggle VBUS
on. When a PD contract above 6V is made, LED5 on the discovery board will light.
To disconnect, toggle VBUS off.

EC command line commands

-   `help` List all available EC console commands
-   `vbus` Toggle VBUS on/off
-   `pd <port> state` Print PD protocol state information
-   `pd <port> swap data` Request data role swap on port
-   `pd <port> swap power` Request power role swap on port
-   `i2cscan` Scan i2c bus for any responsive devices
-   `i2cxfer` Perform an i2c transaction

On the console, you will the PD state machine transitioning through its states
with traces like `C0 st5`. You can always the human readable name of the current
state by doing `pd 0 state` returning something like : `Port C0 CC1, Ena - Role:
SNK-UFP State: SNK_DISCOVERY, Flags: 0x0608` else the numbering of the state is
defined in [include/usb_pd.h](../../include/us_pd.h) by the `PD_STATE_`
constants. It should be by default :

```
[0] DISABLED
[1] SUSPENDED
[2] SNK_DISCONNECTED
[3] SNK_DISCONNECTED_DEBOUNCE
[4] SNK_HARD_RESET_RECOVER
[5] SNK_DISCOVERY
[6] SNK_REQUESTED
[7] SNK_TRANSITION
[8] SNK_READY
[9] SNK_SWAP_INIT
[10] SNK_SWAP_SNK_DISABLE
[11] SNK_SWAP_SRC_DISABLE
[12] SNK_SWAP_STANDBY
[13] SNK_SWAP_COMPLETE
[14] SRC_DISCONNECTED
[15] SRC_DISCONNECTED_DEBOUNCE
[16] SRC_ACCESSORY
[17] SRC_HARD_RESET_RECOVER
[18] SRC_STARTUP
[19] SRC_DISCOVERY
[20] SRC_NEGOCIATE
[21] SRC_ACCEPTED
[22] SRC_POWERED
[23] SRC_TRANSITION
[24] SRC_READY
[25] SRC_GET_SINK_CAP
[26] DR_SWAP
[27] SRC_SWAP_INIT
[28] SRC_SWAP_SNK_DISABLE
[29] SRC_SWAP_SRC_DISABLE
[30] SRC_SWAP_STANDBY
[31] SOFT_RESET
[32] HARD_RESET_SEND
[33] HARD_RESET_EXECUTE
[34] BIST_RX
[35] BIST_TX
```

## Known Issues

1.  This doc is not finished yet ...

2.  You might need a ChromeOS chroot ...

## Troubleshooting

1.  OpenOCD is not finding the device.

    1.  Check that your USB mini-B cable is connected to the **USB ST-LINK**
        plug on the discovery board.
    2.  What color is the LD1 LED on the board ?

1.  On the I2C bus, SDA/SCL lines are staying always low

    1.  You might be missing some pull-up resistors on the bus.
    1.  Check the [Board configuration](#Board-configuration) section if you
        cannot add external pull-ups.

1.  You got black smoke

    1.  Time to buy a new one.
