For our international Users: "Strom" means Power, and won't be translated in this Document. (EPI-S is s short for EPI-Strom)
- 1 EPI-Strom
- 2 Circuit- and Assembly Diagram
- 3 Firmware for EPI-Strom
- 4 Soldering Jumpers
- 5 Parts list
- 6 Programm Firmware
- 7 Alternative Firmware
- 8 Preparing Start-up
- 9 Startup with the EPI-OSD
Power- und Currentmeasurement for the EPI-OSD
Utilizing the EPI-Strom enables you to display energy consumption values into your EPI-OSD, so you don't have to rely on assumptions and just an absolute Voltage Value, when planing Flight. A further Countermeasurement avoiding for crashes due to empty Lipos.
Circuit- and Assembly Diagram
Firmware for EPI-Strom
You can find the actual Firmware here:
One can find older Firmware-versions in the "archiv"-subdirectory.
SJ100 / SJ51
If the Operating Voltage and the measurement voltage are different, this Bridge has to remain open. If the Measurement Voltage shall be the Operating Voltage, SJ100 has to be shortened. (Lipo Power is used for Operation AND measurement then).
SJ1 / SJ50
SJ1 is used to route 5V to the combined STK500/SPI Connector. This is useful when using the SerCon for Powersupply while programming or use the EPI-OSD for Powersupply of the EPI-S. If doing so, you can leave the linear regulator as well as the two Cap's C2 and C3.
Only ab Board revision 1.2
With this Jumper you connect the LiPo-Minus with the GND of teh EPI-Strom-Board.
This is for alternativ use of this Board
(Italic types are on the bottom side)
|1||1N4004 MELF||Reverse Voltage Protection Diode||D101||SMD 1N 4004|
|2||10K||R1, R101||SMD-0805 10,0K|
|8||100nF||C1, C100, C101, C102, C103, C104, C105, C106||X7R-G0805 100N|
|2||10µ||C2, C3||SMD ELKO 10/16|
|1||7805L||Don't assemble when using in conjunction with the EPI-OSD||IC2||µA 78L05|
|1||ACS750LCA-050||Adapt the the Current you want to measure.||IC1||not available at Reichelt|
|1||MA02-5EDGE||X4||SL 2X10G 2,54|
|1||MEGA8-AI||IC100||ATMEGA 8L8 TQ|
|1||SMD ZD 5,6||ZENER-DIODE SOT23||D100||SMD ZD 56|
|1||gn||LED100||SMD-LED 0805 GN|
|1||EPI-Strom-Platine||You will need this for sure ;>||Not available at Reichelt, just Akku Seins ;)|
Grab the Reichelt Partlist here: *klixx*
V. 1.1 and 1.2
(part-numbers >= 50 are on the bottom-side)
|1||1N4004 MELF||Reverse Voltage Protection Diode||D51||SMD 1N 4004|
|1||Siehe Schematic - the value depents on the voltage to be measured||R2|
|2||4k7||R1, R52||SMD-0805 4,70K|
|2||10K||R4, R51||SMD-0805 10,0K|
|2||22pF||C53, C56||NPO-G0805 22P|
|8||100nF||C1, C50, C51, C52, C54, C55, C57, C58||X7R-G0805 100N|
|2||10µ||C2, C3||SMD ELKO 10/16|
|1||8MHz||this has been added for more accurate operation of the serial connection||Q1||8,0000-HC49U-S|
|1||78L05||Do not populate this while using with EPI-OSD!||IC2||µA 78L05|
|1||ACS750LCA-xxx||Adapt the the Current you want to measure.||IC1||Mot available at Reichelt|
|1||MA02-5EDGE||X4||SL 2X10G 2,54|
|1||MEGA8-AI||IC50||ATMEGA 8L8 TQ|
|1||SMD ZD 5,6||ZENER-DIODE SOT23||D50||SMD ZD 5,6|
|1||rot||LED50||SMD-LED 0805 RT|
|1||EPI-Strom-Platine V1.1||You shurly will need this :-)||Not available at Reichelt - AKKU-seins (or our Partner-Shops) are questioned here|
Grab the Reichelt Partlist here: *klick me*
In this tutorial we use the Sercon and Ponyprog2000. You still can use alternatives to that (avrdude etc, mkusb etc) for programming, may we'll desribe them later here.
Then we Connect the EPI-S to the ISP Connector of the sercon, Jumper is shortened. The Mega8 needs to get external Power, we can do that by supplying 5V to SIO Pin2 of the Sercon, and put GND to Pin7. The LED of the Sercon should start glowing.
Set Fuses as follows:
Hardware V. 1.0
In Hex Notation: 0xD7, 0xE4
Hardware V. 1.1
In Hex Notation: 0xD7, 0xFF
Burning the Firmware
After that we write the EPI-S Firmware as well as the eeprom File to the Device. The green LED on the EPI-S should start glowing.
This could look like this:
THE FOLLOWING PICTURE IS USED TO DEMONTRATE THE EXTERNAL POWERSUPPLY VIA SERCON! FOR SETTING FUSES AND FLASHING THE FIRMWARE YOU NEED A COMPLETE 10 WIRE CABLE!
For the EPI-Strom-Board there is also a alternative Firmware.
Please look at: http://www.mylifesucks.de/oss/c-strom/
First we need to calibrate the EPI-S and tell it, which Currentsensor is mounted. For that we need to login the the EPI-S Shell. To get this work, we connect the EPI-S to the ISP Port of the sercon, jumper open. Keep in mind, that we need a special Cable for that, Line 6 MUST be cut. It's enough if Lines 2,3,8 and 10 are connected.
Such a Cable will ook like this:
(Simply use a cutter between the wires and gently remove some cm's of the lines we don't want)
After that the EPI Shell should work great.
As Terminalprogram under Windows putty is good, take care, that you grab the lates Snapshot release, it has some nifty features we need like "Implicit cr in every LF und implicit lf in every CR" 
Com-Parameter are 19200/8N1 Flowcontrol Xon/Xoff.
This Screencast explains it:
After Connecting we check the Connection by tapping <enter> some times, or type "help".
This could look like:
If you only see weird Characters you most likely have flashed a 57k6 firmware. Take the 19k2 Release instead, it works more reliable for the Shell connection. Remember to write the .eep File after flashing again.
If we're in the Shell now, we can set the Sensortype with "set sf 50" for the 50A Sensor and "set sf 100" for the 100A Sensor.
After that we need to calibrate the EPI-S. It's important that it's only got external power, and no power at the Sensor itsself. Then we type "show strom" and see something like:
20 -2100 -0 20 -2102 -0 20 -2002 -0 20 -2050 -0 19 -2092 -1
Now we set the Zero-Value with "set cz 20" followed by "reset" to restart the EPI-S. Now we type "show strom" again. The First Column should be Values around 0 (+-10) now.
-4 -2100 -0 0 -2102 -0 1 -2002 -0 0 -2050 -0 -1 -2092 -1
Attention: If the First Column shows Values around 512, we're at the limits of the measurement range. It's likely that we have a bad Soldering Point at the Data Lines of the current sensor (the 3 thin connector of the sensor, not the fat ones). Re Solder. You should be able to measure ~2,5Volt at the Sensor Output against GND.
Our EPI-S is now configured and we can connect it to the OSD.
Startup with the EPI-OSD
Because it's handy to get operating power for the EPI-S from the OSD, we keep SJ1 shortened. The EPI-S is connected to the ISP port of the OSD.
YOU HAVE TO MAKE A SPECIAL CABLE TO GET IT WORK. THE LINES 3 AND 8 (RX AND TX) NEED TO BE CUT, otherwise the communication between OSD and EPI-S will fail. Such a cable will look like;
In the OSD Setup You have to activate your Current Sensor now. You should see Voltage and Current Values in the OSD now.,