wiki:Hardware/jCM/dCM3/bHardware

Version 17 (modified by Ilya Chigirev, 8 years ago) (diff)

--

Table of Contents

    Hardware Description

    The new chassis manager uses a completely new set of hardware compared to the older revisions. The design is based around the Lantronix XPort AR module, along with accompanying external hardware for interface to the node. The SDK for this device allows the implementation of custom code which is used to interface and understand CMC instructions.

    Major Hardware Components

    Lantronix XPort AR

    The Xport AR is an embedded device server, produced by Lantronix. It runs off of the Evolution OS®, combined with the custom software written using the Xport AR SDK. The Xport AR acts as the 'brains' of the CM3, handling all the networking tasks, as well the link between the CMC instruction commands, and the physical interface to the node. It has the following basic features:

    Architecture
    CPU Based on the DSTni-EX enhanced 16-bit, 120MHz x86 Architecture
    Memory 1.25 MB RAM and 4 MB FLASH
    Firmware upgradeable via FTP,TFTP, Serial Ports, Internal Web Server
    Diagnostics Built in diagnostics and comprehensive statistics
    Network Interface
    Interface Ethernet 10Base-T or 100Base-TX (Auto-Sensing)
    Connector RJ45
    Layer 3 Protocols TCP, UDP, IP, ARP, ICMP, SSH, SSL, XML, HTTP,
    PPP, PAP, CHAP, DNS, SMTP, RSS, DHCP, BOOTP,
    AutoIP, SNMP, FTP, TFTP, Telnet, CGI
    Serial Interface
    Interface CMOS (Asynchronous, 5V Tolerant)
    Data Rates 300 bps to 230,400 bps (selectable by 1bps increments)
    Characters 7 or 8 data bits
    Parity Odd, even, none
    Stop Bits 1 or 2
    Control Signals RTS, CTS, DSR, any PIO
    Flow Control XON/XOFF, RTS/CTS, User Selectable Characters

    The GPIOs are used to control the solid state relays used to power the node on/off and reset the node, as well as monitor the 'hardware status', see the next section for details on this.

    More information on the Xport AR can be found here, and documentation on the device can be found here.

    Voltage Monitor

    The CM3 has a PC voltage monitoring chip installed, the DS1780E+. This chip monitors the +5V, +12V, and temperature of the air in the case. The voltage levels are taken from the floppy connector (J2) which feed directly into the chip and communicates that information over I²C to the Xport AR. However the I²C is not active on the Xport AR, and so there is no way to effectively get accurate voltage and temperature data about the node.

    The 'status' (i.e. on or off) of the node depends on the voltage levels of the power supply (PS), so as a work around for the lack of I²C support the current hardware version of the CM3 has the 5V line feed directly into one of the GPIO (set as an input) and if that is high the PS is on, and so the node is also on. Hopefully I²C will get some support in the future from Lantronix. Presently R4 and R14 is installed and R8 is left open. If I²C is to be implemented then R4 and R14 would have to be removed by hand, and R8 installed.

    RS232 Level Shifter

    The RS232 level (MAX3232) shifter takes the TTL compliant voltage levels from the Tx and Rx lines of the Xport AR and converts them to RS232 voltage standards (and vice versa). there is also 2 sets or resistors R15 & R16, and R17 & R18, which correspond to build in crossover or straight through signals. If R15 and R16 are installed then a straight cable is used to connect to the node serial port and if R17 and R18 are installed a null modem (or crossover) cable must be used. This is the sase for revision 4 of the CM3 board, the previous revision 3 had rotary switches rather than 0 ohm resistors. Also note that presently the RTS and CTS signals have to be shorted manually on the 5x2 100mil header in order for serial redirection to work. This was an oversight in the design and will be fixed in the next run.

    Solid State Relays

    There are two solid state relays (AQV201A) that act as an intermediary to simulate the button press corresponding to a reset and power button for the node motherboard. Important to note, is that the power and reset commands will not work is one of the two output sides of the relays is ties to power or ground, it must be a floating power/closed, and not shorting one pin to ground.

    Attachments (9)

    Download all attachments as: .zip