USB connection shown. Details on the enclosure at
OKW enclosures .
The ethernet version is software compatible with
the ARMweb, refer to those pages for more
information.
The USB version uses the standalone ARMbasic compiler on the PC.
25 pins available to the user, 6 of which can be analog inputs, 8 high current drivers, 3 digital IOs, and 8 flexible IOs
The LPC2138 is used with 512K Flash and 32K of SRAM.
Optional connections to USB, 10Mb Ethernet, or RS-485 (with optional isolation)
picture shown without screw terminals for clarity
Board 7-40V DC. This voltage is reduced with a switching regulator for the 3.3V internal board supply.
High Current Driver (ULN2803 ) 5-50V. This can be a seperate supply from the Board input power, or can be the same supply. It is a required connection for relay drivers to provide a path for current when the relay coil is turned off, it does not have to be the power supply for the board in this case, but it can be.
For volume customers the power supply can be stuffed to accept a regulated 3.3V supply directly, this is done by omitting the switching power supply and adding an appropriate ferrite bead at L5.
The schematic is too large to include on this page, but is downloaded into the /Program files/Coridium/Schematic directory. Is also available here..
Enclosure
OKW B6704100 The kits include custom cutouts for either Ethernet or USB connections. Mechanical drawing for the enclosure is here ,
All the following options can be configured by the user, by optionally stuffing the through-hole components in the DIN rail kit. Coridium will configure boards when 10 or more are ordered.
These may configured for 4-20 mA sensors, with resistor dividers, or as digital inputs. These inputs have diode clamps to 3.3V and GND.
4-20mA sensor --
load 150 ohm SIP into R17
suggested components
Bourns 4600X Bussed SIP resistor
Bourns 4100R Isolated DIP resistor
A/D resistor divider --
load R15 DIP resistor and R14 SIP with appropriate values
AD = Vin * R14/(R14+R15)
Source impedance to AD should be less than 10K.
digital IO --
load R15 with 100 or 1K
digital IO (pulldown)--
load R15 with 100, R14 with 10K
digital IO (pullup) --
load R15 with 100, R14 with 10K
These may use a high sink current driver, or configured as digital IOs with optional pullups or pulldowns
High Current drive --
This driver can sink a surge current of 500mA upto 50V, this driver is a ULN2803 .
suggested components
TI ULN2803AN
Toshiba ULN2803APG
STmicro ULN2803A
digital IO --
digital IO (pulldown) --
digital IO (pullup) --
These may be configured as 8 digital IOs (with and without pullup/pulldown), opto-isolated inputs or outputs, or differential inputs or outputs. They are arranged in 2 groups of 4 so that there can be 2 opto-isolated input and 2 opto-isolated outputs.
opto-isolated input --
suggested components
Liteon LTV-827
Fairchild
MCT9001
Toshiba TLP621-2
opto-isolated output --
same components as above, rotated 180 degrees
bidirectional RS-422 driver --
suggested components
National DS75176BN
TI
SN75176AP
bidirectional RS-422 driver with termination --
suggested components
Bourns 4600 Isolated SIP
resistor
digital IO --
digital IO (pulldown) --
digital IO (pullup) --
These may be configured as staight thru, or with pullups or pulldowns
digital IO --
shown with 100 ohm series
digital IO (pulldown) --
shown with 10K pulldown and 100 series
digital IO (pullup) --
shown with 10K pullup and 100 series
Rev 3
This revision adds the diode and resistor needed for charging an ML2020 battery. That battery can be mounted on the backside of the board as illustrated below
Rev 2
To connect a battery, remove R23, and use the Vbat via to connect, a resistor-Schottky diode-battery connection (suggested schematic below)
GND and 3.3V are available on either side of C7
A 32 KHz crystal (such as the Citizen CMR200TB32.768KDZFTR) can be connected at Y2, with the two 22pF startup caps on the bottom/circuit side of the board.