5ba93f2c13
* Add detailed hardware info for Helios64
- Button
- Ethernet
- Front Panel
- GPIO
- I2C
- Jumper
- LED
- M.2
- PMIC
- PWM Fan
- RTC
- SATA
- SPI
- UEXT
- UPS
- USB
* Cosmetic upgrade and adapt to latest mkdocs-material version
Co-authored-by: nurix <nurix@pnsnc.local>
Co-authored-by: Aditya Prayoga <aditya@kobol.io>
135 lines
4.2 KiB
Markdown
135 lines
4.2 KiB
Markdown
Helios64 supports I2C bus for low-speed communication between devices like microcontrollers, EEPROMs, A/D and D/A converters, I/O interfaces and other similar peripherals. In order to communicate with each I2C slave device you will need an address and communication scenario.
|
|
|
|
## I2C bus on Helios64 / RK3399
|
|
|
|
The I2C controller on RK3399 supports following features:
|
|
|
|
- 9 on-chip I2C controllers
|
|
- Multi-master I2C operation
|
|
- Support 7bits and 10bits address mode
|
|
- Serial 8bits oriented and bidirectional data transfers can be made
|
|
- Software programmable clock frequency
|
|
- Data on the I2C-bus can be transferred at rates of up to 100 kbit/s in the Standardmode, up to 400 kbit/s in the Fast-mode or up to 1 Mbit/s in Fast-mode Plus
|
|
|
|
|
|
**Note:** In the implementation we divided the I2C controller into 2 categories:
|
|
|
|
* Internal Bus, reserved for the system
|
|
* Externel Bus, allocated for user application
|
|
|
|
## Internal Bus
|
|
|
|
!!! Warning
|
|
Theses buses and addresses should not be accessed directly by user. Incorrect configuration can damage the board.
|
|
|
|
Bus 0:
|
|
|
|
Slave | Address | Description|
|
|
------- | ------ |------ |
|
|
RK808-D | 0x1b | |
|
|
SYR837 | 0x40 | |
|
|
SYR838 | 0x41 | |
|
|
|
|
Bus 2:
|
|
|
|
Slave | Address | Description|
|
|
------- | ------ |------ |
|
|
NCT75 | 0x4c | |
|
|
PCA9655 | 0x21 | |
|
|
|
|
Bus 4:
|
|
|
|
Slave | Address | Description|
|
|
------- | ------ |------ |
|
|
FUSB302 | 0x22 | |
|
|
|
|
Above list also includes buses number 1,3,5 which are reserved for system use, therefore not accessible to the user.
|
|
|
|
## External Bus
|
|
|
|
Helios64 exposes Bus number 7 and 8 respectively on **P2** and **P1** headers.
|
|
|
|
All the I2C buses on the board are using voltage level of 3.3V. Note that Helios64 is integrated with level translator and pull up resistor.
|
|
|
|
Please take caution of the reserved address when you use the I2C interface, below is the reserved address list:
|
|
|
|
Slave Address | R/W Bit | Description
|
|
--------------|---------|-------------------
|
|
000 0000 | 0 | General call address
|
|
000 0000 | 1 | START byte(1)
|
|
000 0001 | X | CBUS address(2)
|
|
000 0010 | X | Reserved for different bus format (3)
|
|
000 0011 | X | Reserved for future purposes
|
|
000 01XX | X | Hs-mode master code
|
|
111 10XX | X | 10-bit slave addressing
|
|
111 11XX | X | Reserved for future purposes
|
|
|
|
### I2C Header (P1)
|
|
|
|
Helios64 board exposes I2C Bus 8 on header P1.
|
|
|
|
|
|
|
|
This I2C device works with 3 pin bus (SDA, SCL, and GND), and also in band addressing. Below is the header pin-out:
|
|
|
|
|
|
|
|
### UEXT Header (P2)
|
|
|
|
The I2C Bus 7 can be found on the [UEXT header (P2)](/helios64/uext).
|
|
|
|
|
|
|
|
|
|
|
|
Below is the full pinout of the UEXT header:
|
|
|
|
Pin No | Description
|
|
--------|-------------
|
|
1|3.3V
|
|
2|GND
|
|
3|TXD (UART)
|
|
4|RXD (UART)
|
|
5|SCL (I2C)
|
|
6|SDA (I2C)
|
|
7|MISO (SPI)
|
|
8|MOSI (SPI)
|
|
9|SCK (SPI)
|
|
10|SSEL (SPI)
|
|
|
|
## Usage under Linux
|
|
|
|
Below table list the I2C external bus device name as detected under Linux:
|
|
|
|
Bus number | Device Block | Description |
|
|
-----------|--------------|--------------|
|
|
7 | /dev/i2c-7 | |
|
|
8 | /dev/i2c-8 | |
|
|
|
|
### Checking the I2C Communication under linux
|
|
|
|
In order to communicate with the I2C devices, first we need to identify the I2C bus. By performing scan you can see whether the system can detect device.
|
|
|
|
1. Install the Linux i2c tools.
|
|
|
|
```
|
|
$ sudo apt-get install i2c-tools
|
|
```
|
|
|
|
2. Use **i2cdetect** tool to scan I2C Bus 8.
|
|
|
|
```
|
|
root@helios64:~# i2cdetect -y 8
|
|
|
|
0 1 2 3 4 5 6 7 8 9 a b c d e f
|
|
00: -- -- -- -- -- -- -- -- -- -- -- -- --
|
|
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
|
|
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
|
|
30: -- -- -- -- -- -- -- -- -- -- -- -- 3c -- -- --
|
|
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
|
|
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
|
|
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
|
|
70: -- -- -- -- -- -- -- --
|
|
```
|
|
|
|
Here we can see there is a device detected at the address 0x3c. If you have connected more than just one I2C device on the **P1** header, there will be more devices with different addresses detected on the bus.
|