Difference between revisions of "2-CH RS485 HAT"
(Created page with "File:Example.jpg{{Infobox item |img=300px|link=https://www.waveshare.com/rs485-can-hat.htm | RS485 CAN HAT |caption=2-CH RS485 HAT for Raspbe...") |
|||
(31 intermediate revisions by 2 users not shown) | |||
Line 1: | Line 1: | ||
− | + | <font size="4px"> | |
− | |img=[[File:2-CH-RS485-HAT-1.jpg|300px|link=https://www.waveshare.com/rs485 | + | {{Infobox item |
+ | |name=2-CH RS485 HAT | ||
+ | |img=[[File:2-CH-RS485-HAT-1.jpg|300px|link=https://www.waveshare.com/2-ch-rs485-hat.htm]] | ||
|caption=2-CH RS485 HAT for Raspberry Pi | |caption=2-CH RS485 HAT for Raspberry Pi | ||
+ | |category=[[:Category:Modules|Modules]], [[:Category:Raspberry Pi|Raspberry Pi]] | ||
|brand=Waveshare | |brand=Waveshare | ||
|{{#urlget:amazon|default}}=display | |{{#urlget:amazon|default}}=display | ||
|website_cn=[http://www.waveshare.net/shop/2-CH-RS485-HAT.htm 官方中文站点] | |website_cn=[http://www.waveshare.net/shop/2-CH-RS485-HAT.htm 官方中文站点] | ||
|website_en=[https://https://www.waveshare.com/2-ch-rs485-hat.htm Website] | |website_en=[https://https://www.waveshare.com/2-ch-rs485-hat.htm Website] | ||
− | |interface1 = RPi | + | |interface1=RPi |
− | |interface2= RS485 | + | |interface2=RS485 |
|related= | |related= | ||
{{Product List|Mini PC / Raspberry Pi/Expansions}} | {{Product List|Mini PC / Raspberry Pi/Expansions}} | ||
}} | }} | ||
+ | |||
+ | __TOC__ | ||
== Introduction == | == Introduction == | ||
− | + | This is a dual-channel isolated RS485 extension board specially designed for raspberry PI, which adopts SC16IS752+SP3485 solution, embed with protection circuits such as power supply isolation, ADI magnetical isolation, and TVS diode, etc. | |
+ | It is easy to control the 2-channel RS485 for auto transceiving via SPI interface. Due to its fast communication, stability, reliability, and safety, it is an ideal choice for fields like industrial automation. | ||
{{Amazon|{{#urlget:amazon|default}}=display | {{Amazon|{{#urlget:amazon|default}}=display | ||
− | |More = [https://www.waveshare.com/rs485 | + | |More = [https://www.waveshare.com/2-ch-rs485-hat.htm More]}} |
+ | |||
+ | = Interfaces = | ||
+ | {|class="wikitable" | ||
+ | |- | ||
+ | | VCC || 3.3V | ||
+ | |- | ||
+ | |PIN||Description | ||
+ | |- | ||
+ | |VCC|| 3.3V/5V Power | ||
+ | |- | ||
+ | |GND|| Ground | ||
+ | |- | ||
+ | |SCLK|| SPI Clock input | ||
+ | |- | ||
+ | |MOSI|| SPI Data input | ||
+ | |- | ||
+ | |MISO|| SPI Data output | ||
+ | |- | ||
+ | |CS|| SPI Chip Selection | ||
+ | |- | ||
+ | |IRQ|| Interrupt output (Interrupt Request) | ||
+ | |- | ||
+ | |EN1|| Channel 1 output enable | ||
+ | |- | ||
+ | |EN2|| Channel 2 output enable | ||
+ | |} | ||
+ | |||
+ | |||
+ | == Working principle == | ||
+ | ===Introduction=== | ||
+ | ---- | ||
+ | This product adopts SC16IS752 as controller. SC16IS752 is a dual-channel high-performance UART expansion chip that supports SPI and I2C interfaces communication. This module uses SPI interface. Onboard power isolation, ADI magnetic coupler isolation, onboard TVS (transient voltage suppression tube), self-recovery fuses, protection diodes, and automatic transceiver switching circuit. It can effectively suppress the surge voltage and transient peak voltage in the circuit, prevent lightning and static electricity, prevent over-voltage, improve the anti-impact ability, can conduct signal isolation, with high dependence, strong anti-interference, low power consumption advantages, etc. | ||
+ | |||
+ | |||
+ | ===Communication protocol=== | ||
+ | ---- | ||
+ | [[File:2-CH-RS485 -HAT-2.png|600px]] | ||
+ | *CS:Slave chip selection, when CS is low, the slave chip is enabled. | ||
+ | *SCLK:SPI communication clock | ||
+ | *MOSI/SI:SPI Communication master sends, slave receives | ||
+ | *MOSI/SI:SPI Communication master receives, slave sends | ||
+ | * Timing Sequence:CPHL=0, CPOL=0 (SPI0) | ||
+ | |||
+ | ==How to use== | ||
+ | We provide C and Python demo codes for Raspberry Pi. A quick testing example is provided in python. | ||
+ | |||
+ | ===Hardware Connection=== | ||
+ | To run examples, you should prepare an external [https://www.waveshare.com/usb-to-rs232-485-ttl.htm RS485 to UART] module, connect it to Channel 1 of 2-CH RS485 HAT. | ||
+ | |||
+ | If you test the 2-CH RS485 HAT with the text.py example, you need to wire Channel 1 and Channel 2 of 2-CH RS485 HAT. | ||
+ | |||
+ | {|border=1; style="width:500px;" | ||
+ | |-style="background:#0000ff; color:white;" align="center" | ||
+ | |485 PIN|| Raspberry Pi(BCM) | ||
+ | |-align="center" | ||
+ | |VCC|| 5V | ||
+ | |-align="center" | ||
+ | |GND|| GND | ||
+ | |-align="center" | ||
+ | ||SCK|| P21 (SPI1 SCLK) | ||
+ | |-align="center" | ||
+ | ||MOSI||P20 (SPI1 MOSI) | ||
+ | |-align="center" | ||
+ | |MISO|| P19 (SPI1 MISO) | ||
+ | |-align="center" | ||
+ | ||CS|| P18 (SPI1 CS) | ||
+ | |-align="center" | ||
+ | |IRQ|| P24 | ||
+ | |-align="center" | ||
+ | |EN1|| P27 | ||
+ | |-align="center" | ||
+ | |EN2|| P22 | ||
+ | |} | ||
+ | |||
+ | ===Software setup=== | ||
+ | *Open the terminal and modify config.txt file by commands: | ||
+ | |||
+ | <pre> | ||
+ | sudo nano /boot/config.txt | ||
+ | </pre> | ||
+ | |||
+ | *Add the line below to the file, the int_pin should be set according to the actual welding: | ||
+ | |||
+ | dtoverlay=sc16is752-spi1,int_pin=24 | ||
+ | *Then restart Raspberry Pi | ||
+ | <pre> | ||
+ | sudo reboot | ||
+ | </pre> | ||
+ | *After rebooting, the driver of SC16IS752 will be loaded into the system kernel. You can run command '''ls /dev''' to check the following devices: | ||
+ | [[File:2-CH-RS485-HAT-3.png|800px]] | ||
+ | |||
+ | ===Install Libraries=== | ||
+ | *Install wiringpi | ||
+ | |||
+ | <pre> | ||
+ | sudo apt-get install wiringpi | ||
+ | # An upgrade may be required for raspberry PI 4B: | ||
+ | cd /tmp | ||
+ | wget https://project-downloads.drogon.net/wiringpi-latest.deb | ||
+ | sudo dpkg -i wiringpi-latest.deb | ||
+ | gpio -v | ||
+ | # Running gpio-v to check if the version is 2.52, If it is not, you need to check the installation again. | ||
+ | </pre> | ||
+ | |||
+ | *Install the python2 library | ||
+ | <pre> | ||
+ | sudo apt-get update | ||
+ | sudo apt-get install python-pip | ||
+ | sudo pip install RPi.GPIO | ||
+ | sudo apt-get install python-serial | ||
+ | </pre> | ||
+ | |||
+ | *Install the python3 library | ||
+ | <pre> | ||
+ | sudo apt-get update | ||
+ | sudo apt-get install python3-pip | ||
+ | sudo pip3 install RPi.GPIO | ||
+ | sudo apt-get install python3-serial | ||
+ | </pre> | ||
+ | |||
+ | |||
+ | ===Test=== | ||
+ | *Download and run the examples: | ||
+ | <pre> | ||
+ | sudo apt-get install p7zip-full | ||
+ | wget http://www.waveshare.net/w/upload/4/44/2-CH_RS485_HAT_code.7z | ||
+ | 7z x 2-CH_RS485_HAT_code.7z | ||
+ | sudo chmod 777 -R 2-CH_RS485_HAT | ||
+ | cd 2-CH_RS485_HAT/ | ||
+ | </pre> | ||
+ | |||
+ | *You can also clone the project from our Github: | ||
+ | <pre> | ||
+ | sudo git clone https://github.com/waveshare/2-CH-RS485-HAT | ||
+ | cd 2-CH-RS485-HAT/ | ||
+ | </pre> | ||
+ | |||
+ | *C program | ||
+ | <pre> | ||
+ | cd c | ||
+ | make clean | ||
+ | make | ||
+ | sudo ./main | ||
+ | </pre> | ||
+ | |||
+ | *Python program | ||
+ | <pre> | ||
+ | cd python | ||
+ | cd examples | ||
+ | sudo python main.py | ||
+ | </pre> | ||
+ | |||
+ | Hardware connection: Channel 1 of the 2-CH RS485 HAT is connected to the USB TO [http://www.waveshare.net/shop/USB-TO-RS232-485-TTL.htm USB TO RS232/485/TTL]:<br/> | ||
+ | [[File:2-CH-RS485-HAT-7 (3).png|800px]] | ||
+ | |||
+ | Connect USB TO [http://www.waveshare.net/shop/USB-TO-RS232-485-TTL.htm USB TO RS232/485/TTL] to the computer, open the serial port assistant software, select the corresponding serial port, and set the baud rate to 115200. | ||
+ | *Run the C program, the data sent by computer will all be received by Raspberry Pi, as below: <br/> | ||
+ | [[File:2-CH-RS485 -HAT-4.png|800px]] | ||
+ | |||
+ | '''Note: The path of the samples is based on the actual directory;''' | ||
+ | |||
+ | *Run the main.py, the data sent by computer will all be received by Raspberry Pi, as below: | ||
+ | [[File:2-CH-RS485 -HAT-5.png|800px]] | ||
+ | |||
+ | '''Note: The path of the samples is based on the actual directory;''' | ||
+ | |||
+ | If you don't have other RS485 devices, you can choose the test method as follow by connecting channel 1 with channel 2: | ||
+ | |||
+ | [[File:2-CH-RS485-HAT-8 (3).png|800px]] | ||
+ | |||
+ | *Running result of test.py : | ||
+ | [[File:2-CH-RS485 -HAT-6.png|800px]] | ||
+ | |||
==Resources== | ==Resources== | ||
− | === | + | ===Documentation === |
− | *[[:File: | + | * [[:File:2-CH_RS485_HAT_SchDoc.pdf|Schematic]] |
− | *[[:File: | + | |
+ | ===Demo code === | ||
+ | * [[:File:2-CH_RS485_HAT_code (1).7z|Demo code]] | ||
+ | *[https://github.com/waveshare/2-CH-RS485-HAT Github] | ||
+ | |||
+ | === Datasheets === | ||
+ | * [[:File:SP3481_SP3485.pdf|SP3481_SP3485.pdf]] | ||
+ | * [[:File:SC16IS752_datasheet.pdf|SC16IS752_datasheet.pdf]] | ||
+ | |||
+ | == FAQ == | ||
− | + | {{FAQ|In the semi-automatic mode (manual mode), the green RXD light or the green TXD light is always on? | |
− | + | |In the semi-automatic mode, the voltage on the EN pin determines whether RS485 is transmitted or received. In the transmit mode, the RXD green light may be always on. In the receive mode, the TXD green light may be always on, which is normal.}} | |
− | + | {{FAQ|485 communication is abnormal, what should I do? | |
− | + | |1). Check if the serial communication of the Raspberry Pi has enabled flow control; | |
− | + | 2). Determine whether A and B of 485 correspond one-to-one with the controlled 485 devices A and B;<br/> | |
− | + | 3). You can use USB to 485 module to communicate with 2-CH RS485 HAT to ensure that there is no problem with the Raspberry Pi settings.}} | |
− | |||
− | |||
− | == | + | ==Supports== |
{{Service00}} | {{Service00}} | ||
+ | </font> |
Revision as of 01:11, 29 October 2019
| ||
Introduction
This is a dual-channel isolated RS485 extension board specially designed for raspberry PI, which adopts SC16IS752+SP3485 solution, embed with protection circuits such as power supply isolation, ADI magnetical isolation, and TVS diode, etc. It is easy to control the 2-channel RS485 for auto transceiving via SPI interface. Due to its fast communication, stability, reliability, and safety, it is an ideal choice for fields like industrial automation.
More |
Interfaces
VCC | 3.3V |
PIN | Description |
VCC | 3.3V/5V Power |
GND | Ground |
SCLK | SPI Clock input |
MOSI | SPI Data input |
MISO | SPI Data output |
CS | SPI Chip Selection |
IRQ | Interrupt output (Interrupt Request) |
EN1 | Channel 1 output enable |
EN2 | Channel 2 output enable |
Working principle
Introduction
This product adopts SC16IS752 as controller. SC16IS752 is a dual-channel high-performance UART expansion chip that supports SPI and I2C interfaces communication. This module uses SPI interface. Onboard power isolation, ADI magnetic coupler isolation, onboard TVS (transient voltage suppression tube), self-recovery fuses, protection diodes, and automatic transceiver switching circuit. It can effectively suppress the surge voltage and transient peak voltage in the circuit, prevent lightning and static electricity, prevent over-voltage, improve the anti-impact ability, can conduct signal isolation, with high dependence, strong anti-interference, low power consumption advantages, etc.
Communication protocol
- CS:Slave chip selection, when CS is low, the slave chip is enabled.
- SCLK:SPI communication clock
- MOSI/SI:SPI Communication master sends, slave receives
- MOSI/SI:SPI Communication master receives, slave sends
- Timing Sequence:CPHL=0, CPOL=0 (SPI0)
How to use
We provide C and Python demo codes for Raspberry Pi. A quick testing example is provided in python.
Hardware Connection
To run examples, you should prepare an external RS485 to UART module, connect it to Channel 1 of 2-CH RS485 HAT.
If you test the 2-CH RS485 HAT with the text.py example, you need to wire Channel 1 and Channel 2 of 2-CH RS485 HAT.
485 PIN | Raspberry Pi(BCM) |
VCC | 5V |
GND | GND |
SCK | P21 (SPI1 SCLK) |
MOSI | P20 (SPI1 MOSI) |
MISO | P19 (SPI1 MISO) |
CS | P18 (SPI1 CS) |
IRQ | P24 |
EN1 | P27 |
EN2 | P22 |
Software setup
- Open the terminal and modify config.txt file by commands:
sudo nano /boot/config.txt
- Add the line below to the file, the int_pin should be set according to the actual welding:
dtoverlay=sc16is752-spi1,int_pin=24
- Then restart Raspberry Pi
sudo reboot
- After rebooting, the driver of SC16IS752 will be loaded into the system kernel. You can run command ls /dev to check the following devices:
Install Libraries
- Install wiringpi
sudo apt-get install wiringpi # An upgrade may be required for raspberry PI 4B: cd /tmp wget https://project-downloads.drogon.net/wiringpi-latest.deb sudo dpkg -i wiringpi-latest.deb gpio -v # Running gpio-v to check if the version is 2.52, If it is not, you need to check the installation again.
- Install the python2 library
sudo apt-get update sudo apt-get install python-pip sudo pip install RPi.GPIO sudo apt-get install python-serial
- Install the python3 library
sudo apt-get update sudo apt-get install python3-pip sudo pip3 install RPi.GPIO sudo apt-get install python3-serial
Test
- Download and run the examples:
sudo apt-get install p7zip-full wget http://www.waveshare.net/w/upload/4/44/2-CH_RS485_HAT_code.7z 7z x 2-CH_RS485_HAT_code.7z sudo chmod 777 -R 2-CH_RS485_HAT cd 2-CH_RS485_HAT/
- You can also clone the project from our Github:
sudo git clone https://github.com/waveshare/2-CH-RS485-HAT cd 2-CH-RS485-HAT/
- C program
cd c make clean make sudo ./main
- Python program
cd python cd examples sudo python main.py
Hardware connection: Channel 1 of the 2-CH RS485 HAT is connected to the USB TO USB TO RS232/485/TTL:
Connect USB TO USB TO RS232/485/TTL to the computer, open the serial port assistant software, select the corresponding serial port, and set the baud rate to 115200.
- Run the C program, the data sent by computer will all be received by Raspberry Pi, as below:
Note: The path of the samples is based on the actual directory;
- Run the main.py, the data sent by computer will all be received by Raspberry Pi, as below:
Note: The path of the samples is based on the actual directory;
If you don't have other RS485 devices, you can choose the test method as follow by connecting channel 1 with channel 2:
- Running result of test.py :
Resources
Documentation
Demo code
Datasheets
FAQ
{{{5}}}
2). Determine whether A and B of 485 correspond one-to-one with the controlled 485 devices A and B;
{{{5}}}
Supports
Support
If you require technical support, please go to the Support page and open a ticket.