V 4.8 Revised 7/20 EZO-ORP ™ Embedded ORP Circuit Reads ORP Range -1019.9mV − 1019.9mV Accuracy +/– 1mV Response time 1 reading per sec Supported probes Any type & brand Calibration Temp compensation Data protocol Single point N/A UART & I2C Default I2C address 98 (0x62) Operating voltage 3.3V − 5V Data format ASCII PATENT PROTECTED Written by Jordan Press Designed by Noah Press This is an evolving document, check back for updates.
This is sensitive electronic equipment. Get this device working in a solderless breadboard first. Once this device has been soldered it is no longer covered by our warranty. This device has been designed to be soldered and can be soldered at any time. Once that decision has been made, Atlas Scientific no longer assumes responsibility for the device’s continued operation. The embedded systems engineer is now the responsible party.
Table of contents Circuit dimensions Power consumption Absolute max ratings Operating principle 4 4 4 5 UART UART mode Receiving data from device Sending commands to device LED color definition UART quick command page LED control Find Continuous reading mode Single reading mode Calibration Export calibration Import calibration Naming device Device information Response codes Reading device status Sleep mode/low power Change baud rate Protocol lock Factory reset Change to I2C mode Manual switching to I2C 3
EZO circuit dimensions TM 13.97mm (0.55”) 20.16mm (0.79”) 5.8mm (0.22”) 8.38mm (0.32”) 1mm Ø 10.8mm (0.4”) Power consumption Absolute max ratings 5V 3.3V 4 LED MAX STANDBY ON 18.3 mA 16 mA OFF 13.8 mA 13.8 mA ON 14.5 mA 13.9 mA OFF 13.3 mA 13.3 mA SLEEP Parameter MIN 1.16 mA Storage temperature (EZO™ ORP) -65 °C Operational temperature (EZO™ ORP) -40 °C VCC 3.3V 0.995 mA TYP MAX 125 °C 25 °C 5V 85 °C 5.5V Copyright © Atlas Scientific LLC r 0.
Operating principle ORP stands for oxidation/reduction potential. Oxidation is the loss of electrons and reduction is the gain of electrons. The output of the probe is represented in millivolts and can be positive or negative. Just like a pH probe measures hydrogen ion activity in a liquid; an ORP probe measures electron activity in a liquid. The ORP readings represents how strongly electrons are transferred to or from substances in a liquid.
When reading the ORP of a liquid that has very few electrons available for transfer ORP readings can appear to be inconsistent. The water is unreactive and has only trace amounts of electron movement. These readings are equivalent to the readings you see with an unconnected multimeter. -234.6 Reading A B A 24.2 Reading B 606.
Power and data isolation The Atlas Scientific EZO™ ORP circuit is a very sensitive device. This sensitivity is what gives the ORP circuit its accuracy. This also means that the ORP circuit is capable of reading micro-voltages that are bleeding into the water from unnatural sources such as pumps, solenoid valves or other probes/sensors. When electrical noise is interfering with the ORP readings it is common to see rapidly fluctuating readings or readings that are consistently off.
This schematic shows exactly how we isolate data and power using the ADM3260 and a few passive components. The ADM3260 can output isolated power up to 150 mW and incorporates two bidirectional data channels. This technology works by using tiny transformers to induce the voltage across an air gap. PCB layout requires special attention for EMI/EMC and RF Control, having proper ground planes and keeping the capacitors as close to the chip as possible are crucial for proper performance.
Correct wiring Carrier board RX TX GND VCC Bread board via USB Bread board USB carrier board PWR GND TX RX RX TX 1 5 10 15 20 1 A A 5 10 15 20 A B B B C C C C D D D D E E E E B F F F F G G G G H H H H I I I J 1 5 15 15 20 J 1 J USB A Part # G2-USB-ISO I 5 15 15 20 J Part # ISCCB Part # COM-104 VCC OFF GND TX Electrically Isolated EZO™ Carrier Board RX Isolated Carrier Board Part # ISCCB-2 Incorrect wiring Extended leads Sloppy s
NEVER EXTEND THE CABLE WITH CHEAP JUMPER WIRES! A 1 5 10 15 20 A B B C C D D E E F F G G H H I I J J 1 5 15 15 20 DO NOT CUT THE PROBE CABLE WITHOUT REFERING TO THIS DOCUMENT! 10 Copyright © Atlas Scientific LLC
DO NOT MAKE YOUR OWN UNSHIELDED CABLES! A 1 5 10 15 20 A B B C C D D E E F F G G H H I I J J 1 5 15 15 20 ONLY USE SHIELDED CABLES.
Calibration theory 152.1 197.3 210.6 295.7 306.2 315.7 315.7 315.7 315.7 315.7 315.7 Simple calibration Advanced calibration mode mode The most important part of calibration is watching the readings during the calibration process. Unstabilized It's easiest to calibrate the device in its default state (UART mode, with continuous readings enabled). Stabilized Send Switching the device to I2C mode after calibration will not affect the stored calibration.
Single point calibration Remove the soaker bottle and rinse off the ORP probe. Insert the ORP probe directly into the 225mV calibration solution bottle, and let the probe sit in the calibration solution until the readings stabilize (small movement from one reading to the next is normal). 10 10 10 −−60 −60 60 sec sec sec 342.0 315.2 268.7 240.1 240.1 240.1 240.1 cal,225 *OK 225.0 225.0 Unstabilized Stabilized Once the readings have stabilized, issue the calibration command.
Default state UART mode Baud 9,600 Readings continuous Speed 1 reading per second LED on 1,000 ms 14 Green Cyan Standby Taking reading Copyright © Atlas Scientific LLC Transmitting
Available data protocols Default Unavailable data protocols SPI Analog RS-485 Mod Bus 4–20mA 15 Copyright © Atlas Scientific LLC r 0.
UART mode Settings that are retained if power is cut Baud rate Calibration Continuous mode Device name Enable/disable response codes Hardware switch to I2C mode LED control Protocol lock Software switch to I2C mode Settings that are NOT retained if power is cut Find Sleep mode r 0.
UART mode 8 data bits 1 stop bit Baud no parity no flow control 300 1,200 2,400 9,600 default 19,200 38,400 57,600 115,200 TX RX RX TX RX Data in TX TX RX Data out Vcc CPU 3.3V – 5.
Receiving data from device 2 parts ASCII data string Carriage return Command Terminator 9,600 baud (default) TX RX CPU 209.6 Receiver Sender Advanced ASCII: 2 Hex: 32 30 39 2E 36 Dec: 18 0 9 SDA SCL (TX) (RX) . 6 SDA SCL (TX) (RX) 50 48 57 46 54 0D 13 SDA SCL (TX) (RX) SDA SCL (TX) (RX) SDA SCL (TX) (RX) Copyright © Atlas Scientific LLC r 0.
Sending commands to device 2 parts Command (not case sensitive) Carriage return ASCII data string Terminator TX RX CPU Sleep Sender Receiver Short Advanced ASCII: S l e e p Hex: 53 6C 65 65 70 0D Dec: 83 108 101 101 112 13 Short 19 Copyright © Atlas Scientific LLC r 0.
LED color definition Green Cyan Purple Red White UART standby Taking reading Changing baud rate Command not understood Find LED ON 5V +2.2 mA 3.3V +0.6 mA 20 Copyright © Atlas Scientific LLC r 0.
UART mode command quick reference All commands are ASCII strings or single ASCII characters. Command Function Baud change baud rate pg. 34 9,600 C enable/disable continuous reading pg. 24 enabled Cal performs calibration pg. 26 n/a Export export calibration pg. 27 n/a Factory enable factory reset pg. 36 n/a Find finds device with blinking white LED pg. 23 n/a i device information pg. 30 n/a I2C change to I2C mode pg. 37 not set Import import calibration pg.
LED control Command syntax L,1 LED on default L,0 LED off L,? LED state on/off? Example Response L,1 *OK L,0 *OK L,? ?L,1 *OK L,1 22 or ?L,0 L,0 Copyright © Atlas Scientific LLC r 0.
Find Command syntax Find LED rapidly blinks white, used to help find device Example Response Find *OK SDA SCL (TX) (RX) 23 This command will disable continuous mode Send any character or command to terminate find. SDA SCL (TX) (RX) SDA SCL (TX) (RX) Copyright © Atlas Scientific LLC r 0.
Continuous reading mode Command syntax C,1 enable continuous readings once per second C,n continuous readings every n seconds (n = 2 to 99 sec) C,0 disable continuous readings C,? continuous reading mode on/off? Example Response C,1 *OK ORP (1 sec) ORP (2 sec) ORP (n sec) C,30 *OK ORP (30 sec) ORP (60 sec) ORP (90 sec) C,0 *OK C,? ?C,1 or ?C,0 or ?C,30 *OK 24 default Copyright
Single reading mode Command syntax R takes single reading Example Response R 209.6 *OK 1,000 ms Green Cyan Standby Taking reading Transmitting 800 ms 25 Copyright © Atlas Scientific LLC r 0.
Calibration Command syntax The EZOTM ORP circuit can be calibrated to any known ORP value Cal,n calibrates the ORP circuit to a set value Cal,clear delete calibration data Cal,? device calibrated? Example Response Cal,225 *OK Cal,clear Cal,? *OK ?Cal,0 or ?Cal,1 *OK Cal,225 209.
Export calibration Command syntax Export: Use this command to download calibration settings Export,? calibration string info Export export calibration string from calibrated device Example Response Export,? 10,120 Response breakdown 10, 120 # of strings to export # of bytes to export Export strings can be up to 12 characters long, and is always followed by Export 59 6F 75 20 61 72 (1 of 10) Export 65 20 61 20 63 6F (2 of 10) (7 more) Expor
Import calibration Command syntax Import,n Import: Use this command to upload calibration settings to one or more devices.
Naming device Command syntax Name,n set name Name,? show name Example Name,zzt Name,? n= ________________ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Up to 16 ASCII characters Response *OK ?Name,zzt *OK Name,zzt *OK 29 Do not use spaces in the name Name,? Name,zzt *OK Copyright © Atlas Scientific LLC r 0.
Device information Command syntax i device information Example Response i ?i,ORP,1.97 *OK Response breakdown ?i, ORP, Device 30 1.97 Firmware Copyright © Atlas Scientific LLC r 0.
Response codes Command syntax *OK,1 enable response *OK,0 disable response *OK,? response on/off? default Example Response R 209.6 *OK *OK,0 209.6 R *OK,? no response, *OK disabled ?*OK,1 Other response codes *ER unknown command *OV over volt (VCC>=5.5V) *UV under volt (VCC<=3.
Reading device status Command syntax Status voltage at Vcc pin and reason for last restart Example Response Status ?Status,P,5.038 *OK Response breakdown ?Status, P, 5.038 Reason for restart Voltage at Vcc Restart codes P powered off S software reset B brown out W watchdog U unknown 32 Copyright © Atlas Scientific LLC r 0.
Sleep mode/low power Command syntax Sleep Send any character or command to awaken device. enter sleep mode/low power Example Response Sleep *OK *SL *WA Any command 5V 3.3V STANDBY SLEEP 16 mA 1.16 mA 13.9 mA 0.995 mA wakes up device Sleep Standby 16 mA 33 Sleep 1.16 mA Copyright © Atlas Scientific LLC r 0.
Change baud rate Command syntax Baud,n RX TX Response Baud,? n= RX change baud rate Example Baud,38400 TX Standby RT standby 34 CPU *OK ?Baud,38400 *OK 300 1200 2400 9600 default 19200 38400 57600 115200 Baud,38400 Green TX RX (reboot) Cyan Purple baud rate Changing Red Taking reading Changing *OK baud rate Command not understood Standby White Find Copyright © Atlas Scientific LLC r 0.
Protocol lock TX RX Command syntax CPU Plock,1 enable Plock Plock,0 disable Plock Plock,? Plock on/off? TX RX CPU Locks device to UART mode.
Factory reset Clears calibration LED on "*OK" enabled Command syntax Factory enable factory reset Example Response Factory *OK Factory (reboot) *OK *RS *RE Baud rate will not change 36 1,000 ms Copyright © Atlas Scientific LLC 1,000 ms r 0.
Change to I2C mode Command syntax I2C,n Default I2C address 98 (0x62) sets I2C address and reboots into I2C mode n = any number 1 – 127 Example Response I2C,100 *OK (reboot in I2C mode) Wrong example Response I2C,139 *ER n > 127 I2C,100 (reboot) Green Blue Cyan Cyan Purple Pur Green Green *OK now in I C mode 2 Changing Chan UART standby UART standby Taking reading Taking reading baud ratebaud 37 Copyright © Atlas Scientific LLC r 0.
Manual switching to I2C • • • • • • • • Disconnect ground (power off) Disconnect TX and RX Connect TX to PGND Confirm RX is disconnected Connect ground (power on) Wait for LED to change from Green to Blue Disconnect ground (power off) Reconnect all data and power TX RX CPU Manually switching to I2C will set the I2C address to 98 (0x62) Example Short Wrong Example Short 38 Disconnect RX line Copyright © Atlas Scientific LLC r 0.
I C mode 2 Settings that are NOT if power is cut Settings that areI2C retained if power is cut The protocol is considerably more complex thanretained the UART assumes the embedded Baud rate (RS–232) protocol. Atlas Scientific Find thismode protocol.
I2C mode I2C address (0x01 – 0x7F) 98 (0x62) default Vcc 3.3V – 5.5V Clock speed 100 – 400 kHz VCC SDA 4.
Sending commands to device C SDA 5 parts SCL Start I2C address Write Command (not case sensitive) Stop VCC 98 (0x62) 0V 0V Example Start ASCII command string 98 (0x62) Write I2C address Sleep Stop Command SDA SCL (TX) (RX) SD (TX) SCL SDA CPU Advanced Address bits SDA A6 A5 A4 A3 A2 The entire command as ASCII with all arguments A1 A0 W ACK First letter of command ACK Last letter of command ACK SCL Start 41 W = low Stop Copyright © Atlas Scientific LLC r 0.
Requesting data from device 7 parts Start I2C address Read Response code Data string 98 (0x62) 1 byte "209.6" Null Stop Terminator (Dec 0) SDA SCL (TX) (RX) SCL SDA CPU 209.6 Advanced Address bits SDA A6 − A0 All bytes after data are Null N bytes of data R ACK Response code ACK Data ACK Data N ACK Null ACK R = High Null SCL Start 1 Dec 42 NACK 50 48 57 46 54 ASCII Stop 0 = 209.6 Dec Copyright © Atlas Scientific LLC r 0.
Response codes After a command has been issued, a 1 byte response code can be read in order to confirm that the command was processed successfully. Reading back the response code is completely optional, and is not required for normal operation.
LED color definition SDA SCL (TX) (RX) SDA SCL (TX) (RX) SDA SCL (TX) (RX) SDA SCL (TX) (RX) SDA SCL (TX) (RX) Blue Green Purple Red White I2C standby Taking reading Changing I C address Command not understood Find 2 LED ON 5V +2.2 mA 3.3V +0.6 mA 44 Copyright © Atlas Scientific LLC r 0.
I2C mode command quick reference All commands are ASCII strings or single ASCII characters. Command Function Baud switch back to UART mode pg. 59 Cal performs calibration pg. 49 Export export calibration pg. 50 Factory enable factory reset pg. 58 Find finds device with blinking white LED pg. 47 i device information pg. 53 I2C change I2C address pg. 57 Import import calibration pg. 51 L enable/disable LED pg. 46 Name set/show name of device pg.
LED control Command syntax L,1 LED on 300ms processing delay default L,0 LED off L,? LED state on/off? Example Response L,1 1 Wait 300ms L,0 Wait 300ms L,? Wait 300ms SDA SCL (TX) (RX) L,1 46 0 Dec Null 1 0 Dec Null 1 ?L,1 Dec 0 ASCII Null SDA SCL (TX) (RX) SDA SCL (TX) (RX) or 1 Dec ?L,0 0 ASCII Null SDA SCL (TX) (RX) L,0 Copyright © Atlas Scientific LLC r 0.
Find 300ms Command syntax Find This command will disable continuous mode Send any character or command to terminate find. LED rapidly blinks white, used to help find device Example Response Find 1 Wait 300ms SDA SCL (TX) (RX) 47 processing delay Dec 0 Null SDA SCL (TX) (RX) SDA SCL (TX) (RX) Copyright © Atlas Scientific LLC r 0.
Taking reading Command syntax R processing delay 900ms return 1 reading Example Response R Wait 900ms 1 209.6 Dec ASCII SDA SCL (TX) (RX) Green 0 Null SDA SCL (TX) (RX) SDA SCL (TX) (RX) Wait 900ms Taking reading Blue Transmitting Standby Short SDA SCL (TX) (RX) 48 SDA SCL (TX) (RX) SDA SCL (TX) (RX) Copyright © Atlas Scientific LLC r 0.
Calibration Command syntax 900ms processing delay Cal,n calibrates the ORP circuit to a set value Cal,clear delete calibration data Cal,? Example The EZOTM ORP circuit can be calibrated to any known ORP value device calibrated? Response Cal,225 1 Wait 900ms Cal,clear Wait 300ms Cal,? Wait 300ms 0 SDA SCL SDA SCL (TX) (RX) (TX) (RX) Dec Null 1 0 Dec SDA SCL SDA SCL (TX) (RX) (TX) (RX) Null 1 ?Cal,0 Dec ASCII 0 Null or 1 ?Cal,1 Dec ASCII Cal,225 209.
Export calibration Command syntax 300ms processing delay Export: Use this command to download calibration settings Export,? calibration string info Export export calibration string from calibrated device Example Response (optional) Export,? Wait 300ms 1 10,120 Dec ASCII 0 Null Response breakdown 10, 120 # of strings to export # of bytes to export Export strings can be up to 12 characters long Export Export Wait 300ms Wait 300ms (1 of 10) ASCII 0 Null 1 65 20 61 20 63 6F (2 of 1
Import calibration processing delay 300ms Command syntax Import,n Import: Use this command to upload calibration settings to one or more devices.
Naming device Command syntax Name,n set name Name,? show name Example Do not use spaces in the name n= ________________ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Up to 16 ASCII characters Response 1 Name,zzt Wait 300ms Name,? Wait 300ms Dec 0 Null 1 ?Name,zzt Dec ASCII Name,zzt SDA SCL (TX) (RX) SDA SCL (TX) (RX) 1 52 processing delay 300ms 0 0 Null Name,? SDA SCL (TX) (RX) SDA SCL (TX) (RX) 1 ?Name,zzt 0 Copyright © Atlas Scientific LLC r 0.
Device information Command syntax 300ms processing delay i device information Example Response i Wait 300ms 1 ?i,ORP, 19.7 Dec ASCII 0 Null Response breakdown ?i, ORP, 1.97 Device 53 Firmware Copyright © Atlas Scientific LLC r 0.
Reading device status Command syntax processing delay 300ms Status voltage at Vcc pin and reason for last restart Example Response Status Wait 300ms 1 ?Status,P,5.038 Dec ASCII 0 Null Response breakdown ?Status, P, 5.038 Reason for restart Voltage at Vcc Restart codes P powered off S software reset B brown out W watchdog U unknown 54 Copyright © Atlas Scientific LLC r 0.
Sleep mode/low power Command syntax Sleep enter sleep mode/low power Example Response Sleep no response Any command wakes up device 5V 3.3V STANDBY SLEEP 16 mA 1.16 mA 13.9 mA 0.995 mA SDA SCL (TX) (RX) SDA SCL SDA SCL (TX) (RX)(TX) (RX) Send any character or command to awaken device. Do not read status byte after issuing sleep command. SDA SCL (TX) (RX) Sleep Standby 55 Sleep Copyright © Atlas Scientific LLC r 0.
Protocol lock Command syntax 300ms Plock,1 enable Plock Plock,0 disable Plock processing delay Locks device to I2C mode.
I2C address change Command syntax 300ms processing delay I2C,n sets I2C address and reboots into I2C mode Example Response I2C,100 device reboot Warning! n = any number 1 – 127 Changing the I2C address will prevent communication between the circuit and the CPU until the CPU is updated with the new I2C address. Default I2C address is 98 (0x62). I2C,100 SDA SCL (TX) (RX) SDA SCL (TX) (RX) SDA SCL (TX) (RX) (reboot) 57 Copyright © Atlas Scientific LLC r 0.
Factory reset Command syntax Factory reset will not take the device out of I2C mode. Factory enable factory reset Example Response Factory device reboot I2C address will not change Clears calibration LED on Response codes enabled Factory SDA SCL (TX) (RX) SDA SCL (TX) (RX) SDA SCL (TX) (RX) (reboot) 58 Copyright © Atlas Scientific LLC r 0.
Change to UART mode Command syntax TX RX TX RX CPU CPU Baud,n switch from I2C to UART Example Response Baud,9600 reboot in UART mode 300 1200 2400 9600 19200 38400 57600 115200 n= SDA SCL (TX) (RX) SDA SCL (TX) (RX) SDA SCL (TX) (RX) SDA SCL (TX) (RX) SDA SCL (TX) (RX) Baud,9600 BlueBlue Green Green SDA SCL (TX) (RX) SDA SCL (TX) (RX) SDA SCL (TX) (RX) SDA SCL (TX) (RX) SDA SCL (TX) (RX) SDA SCL (TX) (RX) (reboot) Changing to UART mode Purple Purple Blue Red RedGreen White Wh C st
Manual switching to UART SDA SCL (TX) (RX) • • • • • • • • SDA SCL (TX) (RX) SDA SCL (TX) (RX) Disconnect ground (power off) Disconnect TX and RX Connect TX to PGND Confirm RX is disconnected Connect ground (power on) Wait for LED to change from Blue to Green Green Disconnect ground (power off) Taking reading Transmitting Reconnect all data and power Blue Standby Example Short SDA SCL (TX) (RX) SDA SCL (TX) (RX) SDA SCL (TX) (RX) Wrong Example Short SDA SCL (TX) (RX) 60 Disconnect RX line SDA SCL
EZO circuit footprint TM 17.78mm (0.7”) 4.0 2.54mm (0.1”) 1 In your CAD software place a 8 position header. 1.05mm Ø 61 2 Place a 3 position header at both top and bottom of the 8 position. 3 Delete the 8 position header. The two 3 position headers are now 17.78mm (0.7”) apart from each other. 17.78mm (0.7”) Copyright © Atlas Scientific LLC r 0.
Datasheet change log Datasheet V 4.8 Moved Default state to pg 14. Datasheet V 4.7 Updated firmware to V2.11 on pg 63. Datasheet V 4.6 Revised response for the sleep command in UART mode on pg 33. Datasheet V 4.5 Revised calibration theory on page 12, and added more information on the Export calibration and Import calibration commands. Datasheet V 4.4 Revised isolation schematic on pg. 10 Datasheet V 4.3 Changed "Max rate" to "Response time" on cover page. Datasheet V 4.
Datasheet V 4.0 Revised definition of response codes on pg 42. Datasheet V 3.9 Revised isolation information on pg 9. Datasheet V 3.8 Revised Plock pages to show default value. Datasheet V 3.7 Added new commands: "Find" pages 23 (UART) & 46 (I2C). "Export/Import calibration" pages 27 (UART) & 49 (I2C). Added new feature to continous mode "C,n" pg 24. Datasheet V 3.6 Revised circuit illustrations throughout datasheet. Datasheet V 3.
Firmware updates V1.5 – Baud rate change (Nov 6, 2014) • Change default baud rate to 9600 V1.6 – I2C bug (Dec 1, 2014) • Fixed I2C bug where the circuit may inappropriately respond when other I2C devices are connected. V1.7 – Factory (April 14, 2015) • Changed “X” command to “Factory” V1.95 – Plock (March 31, 2016) • Added protocol lock feature “Plock” V1.96 – EEPROM (April 26, 2016) • Fixed bug where EEPROM would get erased if the circuit lost power 900ms into startup V1.
Warranty Atlas Scientific™ Warranties the EZO™ class ORP circuit to be free of defect during the debugging phase of device implementation, or 30 days after receiving the EZO™class ORP circuit (which ever comes first). The debugging phase The debugging phase as defined by Atlas Scientific™ is the time period when the EZO™ class ORP circuit is inserted into a bread board, or shield. If the EZO™ class ORP circuit is being debugged in a bread board, the bread board must be devoid of other components.
Reasoning behind this warranty Because Atlas Scientific™ does not sell consumer electronics; once the device has been embedded into a custom made system, Atlas Scientific™ cannot possibly warranty the EZO™ class ORP circuit, against the thousands of possible variables that may cause the EZO™ class ORP circuit to no longer function properly. Please keep this in mind: 1. All Atlas Scientific™ devices have been designed to be embedded into a custom made system by you, the embedded systems engineer. 2.
