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docs/about.md
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# Open-hardware for electrostatic discharge testing (O-ESD) # Open-hardware for electrostatic discharge testing (O-ESD)
O-ESD is open-hardware project for (pre-compliance) [ESD immunity testing](https://en.wikipedia.org/wiki/IEC_61000-4-2) in accordance with IEC/EN 61000-4-2(https://webstore.iec.ch/en/publication/68954) standard. It is a stand-alone battery-powered portable device that can produce low-energy voltage pulses in the range from –15kV to 15kV. All electronic devices must be immune to a certain level of ESD, as ESD happens everyday between humans and electronic devices. O-ESD is open-hardware project for (pre-compliance) [ESD immunity testing](https://en.wikipedia.org/wiki/IEC_61000-4-2) in accordance with [IEC/EN 61000-4-2](https://webstore.iec.ch/en/publication/68954) standard. It is a stand-alone battery-powered portable device that can produce low-energy voltage pulses in the range from –15kV to 15kV. All electronic devices must be immune to a certain level of ESD, as ESD happens everyday between humans and electronic devices.
![Prototype](img_O-ESD_prototype_top_view.png)<br> ![Prototype](img_O-ESD_prototype_top_view.png)<br>
O-ESD is released under [CERN Open Hardware License Version 2 – Strongly Reciprocal](https://o-esd.etf.bg.ac.rs/IMG/cern_ohl_s_v2.txt).<br> O-ESD is released under [CERN Open Hardware License Version 2 – Strongly Reciprocal](https://o-esd.etf.bg.ac.rs/IMG/cern_ohl_s_v2.txt).<br>
The current release is [version 1.0](https://o-esd.etf.bg.ac.rs/forgejo/dragan.olcan/O-ESD/src/branch/main/v1.0).<br> The current release is [version 1.0](https://o-esd.etf.bg.ac.rs/forgejo/dragan.olcan/O-ESD/src/branch/main/v1.0).<br>
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* Single-discharge mode and user-defined pulse repetition. * Single-discharge mode and user-defined pulse repetition.
* User-defined hold time for output voltage for air discharge. * User-defined hold time for output voltage for air discharge.
* Equivalent capacitance seen from the output terminals 100pF. * Equivalent capacitance seen from the output terminals 100pF.
* Equivalent resistance seen from the output terminals 330$\Omega$. * Equivalent resistance seen from the output terminals 330&Omega;.
* ESD pulse in accordance with IEC/EN 61000-4-2. * ESD pulse in accordance with IEC/EN 61000-4-2.
* ESD pulse energy up to 17mJ. * ESD pulse energy up to 17mJ.
* Powered by two 18650 3.7V Li-Ion rechargeable batteries. * Powered by two 18650 3.7V Li-Ion rechargeable batteries.
@ -24,19 +24,20 @@ The O-ESD is powered up (or down) using the toggle switch located on the grip. T
![Grip](img_grip.png)<br> ![Grip](img_grip.png)<br>
Once the O-ESD is powered-up the splash screen should appear for 1 s at the LCD. Afterwards, the main screen of the O-ESD shows up. LCD has four 20-character lines. Each line stands for one item. Items (i.e., lines) are selected by moving the selector “ > ” using up/down buttons.<br> Once the O-ESD is powered-up the splash screen should appear for 1 s at the LCD. Afterwards, the main screen of the O-ESD shows up. LCD has four 20-character lines. Each line stands for one item. Items (i.e., lines) are selected by moving the selector “ > ” using up/down buttons.<br>
If an item has a numeric value selectable by the user, the numeric value can be changed by rotating the knob. Some items have multiple choices (selections) or submenus (sub-items) available and those are accessible by pressing the knob.<br> If an item has a numeric value selectable by the user, the numeric value can be changed by rotating the knob. Some items have multiple choices (selections) or submenus (sub-items) available and those are accessible by pressing the knob.<br>
![UI](img_UI.png) ![UI](img_UI.png)<br><br>
<br> There are two modes of operation:
![Item](img_item_sel.png)<br> * contact discharge and
<br> * air discharge.
There are two modes of operation: (1) contact discharge and (2) air discharge. The default mode is the contact discharge. The sharp conductive tip (electrode) is used for contact discharge and should be placed in the red socket at O-ESD output. For air discharge the rounded conductive tip (electrode) is used and it should be placed in the black socket. O-ESD is intended for use with only one conductive tip (electrode) inserted at a time and with the appropriate mode of operation selected.<br> The default mode is the contact discharge. The sharp conductive tip (electrode) is used for contact discharge and should be placed in the red socket at O-ESD output. For air discharge the rounded conductive tip (electrode) is used and it should be placed in the black socket. O-ESD is intended for use with only one conductive tip (electrode) inserted at a time and with the appropriate mode of operation selected.<br>
The first (top) item on LCD is the battery status. It displays the minimum of relative voltages of the two batteries. If the voltage of a battery drops below 3.5 V, the battery status displays that recharge is needed. Note that O-ESD will work even with very low battery voltage that may irreparably damage the batteries. Battery status has a submenu that presents extended information about each battery.<br> Screen (menu) has four items.<br>
![Battery_extended](img_bat_ex.png)<br> (1) The first (top) item on LCD is the battery status. It displays the minimum of relative voltages of the two batteries. If the voltage of a battery drops below 3.5 V, the battery status displays that recharge is needed. Note that O-ESD will work even with very low battery voltage that may irreparably damage the batteries. Battery status has a submenu that presents extended information about each battery.<br>
The second item is the operation mode. It can be either contact or air as selected by the used.<br> ![Battery_extended](img_bat_ex.png)
The third item is the ESD voltage level. The ESD voltage can be in the range from –12kV to 12kV in the case of contact discharge, or in the range from –15kV to 15kV in the case of air discharge. Note that the sign of the charge (polarity) is defined by the position of the cascade, i.e., it should be placed in the correct position in order that given polarity can be produced at the output.<br> (2) The second item is the operation mode. It can be either contact or air as selected by the used.<br><br>
The forth item (at the bottom of LCD) is<br> (3) The third item is the ESD voltage level. The ESD voltage can be in the range from –12kV to 12kV in the case of contact discharge, or in the range from –15kV to 15kV in the case of air discharge. Note that the sign of the charge (polarity) is defined by the position of the cascade, i.e., it should be placed in the correct position in order that given polarity can be produced at the output.<br><br>
(4) The forth item (at the bottom of LCD) is
* the total number of pulses in the case of the contact discharge or * the total number of pulses in the case of the contact discharge or
* the hold time in seconds for air discharge (i.e., the time window in which the rounded tip is at the predefined voltage until the air discharge happens). * the hold time in seconds for air discharge (i.e., the time window in which the rounded tip is at the predefined voltage until the air discharge happens).<br>
Once the user has selected the mode of operation, ESD voltage level and number of pulses (or hold time), the discharge is initiated by pressing the fire button on the grip. During all the specified discharge(s) cycles, the information about discharge is displayed on LCD and the O-ESD main screen is inaccessible.<br> Once the user has selected the mode of operation, ESD voltage level and number of pulses (or hold time), the discharge is initiated by pressing the fire button on the grip. During all the specified discharge(s) cycles, the information about discharge is displayed on LCD and the O-ESD main screen is inaccessible.<br><br>
The sign (polarity) of the output is determined by the cascade connections to the shaper and the motherboard. The opposite sign is achieved by rotating the cascade for 180 degrees, i.e., the sign of the output is the one printed on the cascade end connected to the shaper. Before disconnecting and rotating the cascade, wait for 10 seconds after the last discharge so that the cascade discharges fully.<br> The sign (polarity) of the output is determined by the cascade connections to the shaper and the motherboard. The opposite sign is achieved by rotating the cascade for 180 degrees, i.e., the sign of the output is the one printed on the cascade end connected to the shaper. Before disconnecting and rotating the cascade, wait for 10 seconds after the last discharge so that the cascade discharges fully.<br>
![Cascade_rotation](img_cascade_rot.png)<br> ![Cascade_rotation](img_cascade_rot.png)<br>
When not in use, O-ESD should be turned off using the toggle switch on the grip.<br> When not in use, O-ESD should be turned off using the toggle switch on the grip.<br>
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### Cascade ### Cascade
The cascade is a separate PCB connected to the motherboard and the cascade with two 2-wire cables with XT60 connectors at each end. The main purpose of the cascade is to provide high-voltage DC for the shaper.<br> The cascade is a separate PCB connected to the motherboard and the cascade with two 2-wire cables with XT60 connectors at each end. The main purpose of the cascade is to provide high-voltage DC for the shaper.<br>
![Cascade_assembly](img_cascade_assembly.png)<br> ![Cascade_assembly](img_cascade_assembly.png)<br>
In order to prevent losses from the corona effect, assembled cascade can be coated can be coated with corona-protective insulating material (e.g. Plastik70 from Kontakt Chemie or similar).<br> In order to prevent losses from the corona effect, assembled cascade can be coated with corona-protective insulating material (e.g. Plastik70 from Kontakt Chemie or similar).<br>
### Shaper ### Shaper
The shaper is a separate PCB connected to the mother board (with 4-wire cable) and the cascade (with 2-wire cable with XT60 connector). The main purpose of the shaper is to generate pulse according to IEC/EN 61000-4-2.<br> The shaper is a separate PCB connected to the mother board (with 4-wire cable) and the cascade (with 2-wire cable with XT60 connector). The main purpose of the shaper is to generate pulse according to IEC/EN 61000-4-2.<br>

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