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This article explains how to establish a serial connection between a Parallella board and any device, which is equipped with a serial terminal. This article uses a PC for a device that the Parallella board is connected to.
The Parallella board is equipped with UART HEADER (J2). These pins are C-MOS 3.3V and single end, and attached to UART of Zyng. These pins are going to be connected to a serial terminal of a PC.
Since The level of a signal at RS-232C (EIA-574) of the PC is between 5 and 12V, the serial connection of PC cannot directly be connected to UART HEADER (J2) of Parallarella. The connection can be established via the voltage converters, which are placed at both PC and Parallella sides.
A LSI, which can be used for a voltage converter, is sold from several chip producers. This article uses the voltage conversion board, which is equipped with ADM3202 of Analog Devices. To use this voltage conversion board, 3.3V or 5V is produced from the power supply of the parallella board. 5V of power source is pulled out from near the DC power jack on the Parallella board. The power is provided from this DC power jack to the voltage conversion board.
- Requirements
Names of Products Qty. Memo 1 RS232 Level Conversion Board (equipped withADM3202ARU) 1 Available at Akizuki's net shop 2 D-Sub 9-pin female (the board above is soldered) 1 Available at Akizuki's net shop 3 D-Sub 9-pin connector shell 1 Available at Akizuki's net shop 4 Cable AWG 26 – 28 4 Four different colors (Red, Black, White , and Green) 5 Pin Housing (for 3-pin) 2 For 2.54mm pitch MIL connector 6 Pin Contact 5 For 2.54mm pitch MIL connector ※ You may select any Pin Housing and Pin Contact as long as they can fit with 2.54mm pitch pin header.
- JP1 at RS232 level conversion board (employing ADM 3202ARU) is going to be soldered.
- The connector of D-Sub 9-pin is soldered to the level conversion board.
- The cables are attached to the level conversion board. In this article, the colors of cables are red, black, white, and green. If you may apply different colors of cables, please attach the cables to their expected pins.
- Each cable is soldered to its counter part, a specific pin of CN1 of the level conversion board. The details of the connections are shown in the table below.
Pin # Color of Cable Type of Signal 1 Black GND 2 Green TX-IN 3 White RX-OUT 4 Not Connected 5 Red DC 5V
- An example of soldering
- As soldering is completed, the level conversion board is stored into the connector case for D-Sub 9-pin.
- At the other side of the cables, please modify as they are shown below. Then, the modified ends are stored into pin sockets.
- Pin contacts are attached to the end of the black, white, and green cables, providing pressure on them. These pin contacts are inserted to the pin housing. The allocation of pins are shown below.
Pin # Color of Cable Type of Signal 1 Green TX 2 White RX 3 Black GND - The other end of the red cable is divided into two. Then, These ends are connected to the 1st terminal and 2nd terminal.
In the picture below, these divided ends of the red cable are held at only the 2nd terminal by giving pressure. Also, you can pull apart the end of the cable into Y-shape, and the ends are held at both the 1st and 2nd terminals by giving pressure. The latter way is easier way to modify the end of the red cable then former one.
1 Red DC 5V 2 Red DC 5V 3 Not Connected
- An example of cables which connectors are attached.
To attach the cables to the Parallella board, please follow the directions shown below.
- Remove the jumper, which is inserted at J14.
- Two connectors of the red cable are attached there. The 1st terminal of the red cable is inserted at J12, which is located near the power jack. The order of the attaching connectors are red, red and empty from the power jack. If the power is supplied from the USB connector side, the order of attaching connector is reversed, and it will be empty, red, and red.
- The connectors of green, white, and black cables are inserted at J2. The first pin of J2 is located near RJ-45 Giga-Ether, and the third pin near the outside of the board.
- An example of the parallella board, which is connected to the cables and D-Sub 9-pin connector.
- Reference Schematic
- 2015/01/26 This article is initially uploaded
SPEC-012-0001A.pdf