# ODYSSEY - STM32MP157C Support
This is the base Nerves System configuration for the [ODYSSEY - STM32MP157C](https://www.seeedstudio.com/ODYSSEY-STM32MP157C-p-4464.html).
This image is from [Seeed](https://www.seeedstudio.com/ODYSSEY-STM32MP157C-p-4464.html).
| Feature | Description |
| -------------------- | ----------------------------------------------------------- |
| CPU | 650MHz Dual-core Arm-Cortex-A7 with Cortex-M4 integrated |
| Memory | 512MB DDR3 RAM |
| Storage | 4GB EMMC and MicroSD |
| Linux kernel | 5.10 w/ RCN patches |
| IEx terminal | UART `ttySTM0` |
| GPIO, I2C, SPI | Yes - [Elixir Circuits](https://github.com/elixir-circuits) |
| ADC | No |
| PWM | Yes, but no Elixir support |
| UART | ttySTM0, ttySTM2 |
| Display | MIPI DSI display interface, not supported yet |
| Camera | DVP camera interface, not supported yet |
| Ethernet | Yes (eth0) |
| WiFi | Yes (wlan0) |
| Bluetooth | Yes (hci0), not confirmed yet |
| Audio | 3.5mm audio interface, not supported yet |
| RTC | 3VRTC battery interface |
## Using
This port currently only runs off a SD card.
The most common way of using this Nerves System is create a project with `mix
nerves.new` and add `stm32mp157c_odyssey` references where needed and in a similar way
to the default systems like `bbb`, etc. Then export `MIX_TARGET=stm32mp157c_odyssey`.
See the [Getting started guide](https://hexdocs.pm/nerves/getting-started.html#creating-a-new-nerves-app)
for more information.
If you need custom modifications to this system for your device, clone this
repository and update as described in [Making custom systems](https://hexdocs.pm/nerves/systems.html#customizing-your-own-nerves-system).
## Networking
The board has one 1 Gbps Ethernet interface and one WiFi interface. Here's an example `:vintage_net`
configuration that enables both of them:
For WiFi configuration, see. https://hexdocs.pm/vintage_net/cookbook.html#normal-password-protected-wifi-wpa2-psk
```elixir
config :vintage_net,
regulatory_domain: "US",
config: [
{"eth0", %{type: VintageNetEthernet, ipv4: %{method: :dhcp}}},
{"wlan0", %{type: VintageNetWiFi}}
]
```
## Serial
This board has one uart and two usart.
| name as tty | name as serial | dts info | dts info | for what |
| ----------- | -------------- | ---------- | -------- | ---------------------------------- |
| ttySTM0 | serial0 | 0x40010000 | uart4 | for debug uart besides barrel jack |
| ttySTM1 | serial1 | 0x5c000000 | usart1 | for AP6236, so can't be used |
| ttySTM2 | serial2 | 0x4000e000 | usart2 | for raspi compatible uart |
## GPIO
GPIO pins for circuits_gpio can be calculated according to the following formula,
```
pin number = <gpio chip name> * 16 + offset
# gpio chip name is A as 0, B as 1 ...
```
So pin number of below image GPIO_H12 is 124, 7 * 16 + 12.
<img src="https://files.seeedstudio.com/wiki/ODYSSEY-STM32MP157C/IMG/GPIO.png" width="500" />
## Known limitations
### eth0 MAC address changes at each boot
This is because the vendor does not provide it.
### Can't read input when using circuits_gpio
See below issue.
[Can't read input until after the output has been configured once when using circuits_gpio](https://github.com/b5g-ex/nerves_system_stm32mp157c_odyssey/issues/3)
### Can't use GPIO_B2
This is because uart4 rx uses it. See below issue.
[Can't use GPIO_B2](https://github.com/b5g-ex/nerves_system_stm32mp157c_odyssey/issues/4)
