Digilent uses cookies to ensure you get the best experience on our websites. By using our site you agree to our use of cookies. Got it! tore log Forum Project Documentation Programmable Logic Microprocessors Instrumentation Pmods Software Search Show pagesource You are here:: Digilent Documentation / Reference / Add-ons / DMM Shield / DMM Shield Reference Manual DMM Shield Reference Manual Table of Contents The DMM Shield is a 5 1/2 Digit digital multimeter, designed for use with Digilent microcontroller boards and FPGA boards that are equipped with the Arduino shield header, see Compatible Boards. The shield is built around the HY3131 module from Hycon Technology, which is an analog front end DMM dedicated chip. The device has 7 measurements functions (AC/DC Voltage, AC/DC Current, Resistance, Diode, Continuity) and is factory calibrated. It can be used out of the box with the compatible system boards. It is accessed through a custom SPI interface, using digital IO pins exposed in the DMM Shield connector. Overview Features Full compatibility with Digilent System Boards featuring the Arduino Shield Provides 4 banana connectors for measurements(Volts/, COM, mAmps, Amps). Floating COM AC/DC voltage and current measurements Diode, continuity measurement/function Resistance measurement Supports SPI connection HY3131 Features in Brief Programmable multifunctional switch network High-resolution, high-speed - ADCs - for high conversion speed, resolution and accuracy Digital RMS circuit - the conversion result is processed by the high-speed calculation of the inner hardware to realize the digital RMS [reference: http://www.hycontek.com/wp-content/uploads/Description-HYCON-EN.pdf] Operational amplifier Multifunctional comparator Peak-Hold measurement circuit - to achieve higher accuracy Low-Pass filter - implements a third order LPF Supports SPI interface connection Compatible Boards The DMM Shield is hardware compatible with all Digilent boards that use the Arduino Shield connector, however, the libraries and out of box experience are written for the following boards: Arty-Z7 uC32TM WF32TM Max32TM Uno32TM Arduino Uno Arduino Due Arduino Mega The DMMShield can be used with both 3.3V and 5V voltage levels existing on the Arduino boards. Note: The pic32 library is written to target the uC32 micro-controller board. For all the other boards from the series, the pin-out might suffer modifications. Specifications Voltage and Power Parameters Min Typical Max Units Power Supply Input Voltage 3.0 3.3 3.6 V Power Supply Input Voltage - 5.0 - V Power Supply Current Consumption - 90 100 mA Ranges Min Max AC Voltage -30 +30 V DC Voltage -50 +50 V AC/DC Current -5 +5 A Resistances 50 50M Accuracy: +/-0.1% on Voltage, Current and 500-5M Resistance measurements; +/-1% on 50 and 50M Resistances measurements Resolution: 5 1/2 Digit Floating COM with on board isolated power supply Protections: 60V PTC for Voltage and resistances and uA 630mA fuse for mA rail 6.3A fuse for A rail Communication: Custom SPI protocol Power DMM Shield is powered by the system board. It uses both 5V0 and 3V3 power supplies. The average consumption of the DMM Shield is 90mA. The DMM shield features on-board power supplies that are used to power the DMM core of the board. The 5V power supply is isolated in order to provide an isolated reference signal for measurements. There are more than one reference signals on the DMM Shield board: GND - Ground for the non-isolated section. References all the signals and voltage rails in the non-isolated section such as 5V0 and 3V3 voltages from the system board, relay driver, flash memory VSS_ISO - Most negative voltage in the isolated section. It is the reference for isolated power supplies VCC5V0_ISO and VCC3V3_ISO as well for all the digital signals in the isolated section COM_ISO - Reference for the DMM measurement. All the measurements done with the DMM Shield will be referenced to COM_ISO signal, through COM connector, J2. The reference is leveled at 1.8V above VSS_ISO AGND_ISO - Reference for all the analog signals in the isolated section. It is connected to the COM_ISO through a 0 resistor Functional Description Connectors and Jumpers The DMM Shield is equipped with the Arduino shield header that provides powering and communication between the DMM Sheild and system board. There are also 4 banana connectors that interface the DMM with the sources and devices that need to be measured. Banana Connectors (J1-J4) J1 (V/) - is used for measuring the AC/DC voltages, Resistances, Diode and Continuity. J2 (COM) - is the reference for all the measurements that can be done with the DMM Shield. COM signal is floating from all the other reference points from the board. J3 (500mA) - is used for measuring AC/DC currents up to 500mA. J4 (5A) - is used for measuring AC/DC currents up to 5A. Arduino Shield Connector (J5-J9): J5 - 1x2 Header - Digital pins J6 - 2x6 Header - Analog pins J7, J8 - 2x8 Headers - Digital pins J9 - 1x8 Header - Power pins For detailed usage of each pin please see the Pinout Table Appendix Pinout Table Appendix. Jumpers: JP1 - Frequency Measurement - Not Implemented Digital Pins Used for Communication SPI Pins The DMM Shield supports SPI communication with both the DMM chip and the EEPROM chip. The hardware interface lines DataIn (DI), DataOut (DO) and Clock (CK) are shared between the two devices, and the Chip Select (CS) lines are separate, allowing the user to access either of them with fewer hardware resources used. The DMM chip is electrically separated from the rest of the circuitry, therefore the communication lines need to be isolated as well. The EEPROM CS line is active high, while the DMM CS line is active low. The reading sequence for SPI DMM communication is the one below: The writing sequence for SPI DMM communication is the one below: The timing for SPI DMM communication is the one below: GPIO Pins There are three GPIO pins used for Relay control: RLU, RLD, RLI. Depending on the type of measurement performed, the corresponding relay/s need to be triggered/commanded using a GPIO pin. The relays RLI, RLU, and RLD are controlled by three digital signals, IO2, IO3, and IO4, from the shield connector. Scales RLI RLU RLD 50M 0 0 1 5M 0 0 1 500k 0 0 1 50k 0 0 1 5k 0 0 1 500 0 0 1 50 0 0 1 50VDC 0 1 0 5VDC 0 1 0 500mVDC 0 0 1 50mVDC 0 0 1 50VAC 0 1 0 5VAC 0 1 0 500mVAC 0 0 1 50mVAC 0 0 1 5ADC 0 0 0 500mADC 0 0 0 50mADC 0 0 0 Scales RLI RLU RLD 5mADC 1 0 0 500uADC 1 0 0 5AAC 0 0 0 500mAAC 0 0 0 50mAAC 0 0 0 5mAAC 1 0 0 500uAAC 1 0 0 Continuity 0 0 1 Diode 0 0 1 In addition to configuring the GPIO pins, setting each scale assumes the configuration of some registers. The HY3131 chip provides 23 configurable registers. Scales INTE R20 R21 R22 R23 R24 R25 R26 R27 R28 R29 R2A R2B R2C R2D R2E R2F R30 50M 0x00 0xC0 0xCF 0x17 0x93 0x85 0x00 0x00 0x55 0x55 0x00 0x00 0x08 0x00 0x00 0x80 0x86 0x80 5M 0x00 0xC0 0xCF 0x17 0x93 0x85 0x00 0x00 0x55 0x55 0x00 0x00 0x08 0x00 0x80 0x80 0x86 0x80 500k 0x00 0xC0 0xCF 0x17 0x93 0x85 0x00 0x00 0x55 0x55 0x00 0x00 0x08 0x00 0x08 0x80 0x86 0x80 50k 0x00 0xC0 0xCF 0x17 0x83 0x85 0x00 0x00 0x55 0x00 0x00 0x00 0x40 0x00 0x06 0x44 0x94 0x80 5k 0x00 0xC0 0xCF 0x17 0x83 0x85 0x00 0x00 0x55 0x00 0x00 0x00 0x40 0x60 0x00 0x44 0x94 0x80 500 0x00 0xC0 0xCF 0x17 0x83 0x35 0x00 0x00 0x55 0x00 0x00 0x00 0x40 0x06 0x00 0x44 0x94 0x80 50 0x00 0xC0 0xCF 0x17 0x83 0x35 0x01 0x00 0x55 0x00 0x00 0x00 0x40 0x06 0x00 0x44 0x94 0x80 50VDC 0x00 0x60 0x00 0x17 0x8B 0x01 0x11 0x00 0x55 0x31 0x00 0x22 0x00 0x00 0x09 0x28 0xA0 0x80 5VDC 0x00 0x60 0x00 0x17 0x8B 0x01 0x11 0x00 0x55 0x31 0x00 0x22 0x00 0x00 0x90 0x28 0xA0 0x80 500mVDC 0x00 0xC0 0x00 0x17 0x8B 0x85 0x11 0x00 0x55 0x31 0x00 0x00 0x00 0x00 0x00 0x00 0x90 0x80 50mVDC 0x00 0x00 0x00 0x17 0x8B 0x35 0x11 0x00 0x55 0x31 0x00 0x00 0x00 0x00 0x00 0x00 0x90 0x80 50VAC 0x00 0xF2 0xDD 0x07 0x03 0x52 0x10 0x80 0x25 0x31 0xF8 0x22 0x00 0x00 0x0D 0x28 0xA0 0xFF 5VAC 0x00 0xF2 0xDD 0x07 0x03 0x52 0x10 0x80 0x25 0x31 0xF8 0x22 0x00 0x00 0xD0 0x88 0xA0 0xFF 500mVAC 0x00 0x92 0xDD 0x07 0x03 0x52 0x10 0x80 0x25 0x11 0xF8 0x00 0x00 0x00 0x00 0x00 0x90 0x80 50mVAC 0x00 0x52 0xDD 0x07 0x03 0x00 0x13 0x80 0x25 0x11 0xF8 0x00 0x00 0x00 0x00 0x00 0x90 0x80 5ADC 0x00 0x00 0x00 0x17 0x8B 0x95 0x11 0x00 0x55 0x31 0x00 0x00 0x00 0x00 0x00 0x00 0x80 0x80 500mADC 0x00 0x00 0x00 0x17 0x8B 0x95 0x11 0x00 0x55 0x31 0x00 0x00 0x00 0x00 0x00 0x00 0x80 0x80 50mADC 0x00 0x00 0x00 0x17 0x8B 0x35 0x11 0x00 0x55 0x31 0x00 0x00 0x00 0x00 0x00 0x00 0x80 0x80 5mADC 0x00 0x00 0x00 0x17 0x8B 0x95 0x11 0x00 0x55 0x31 0x00 0x00 0x00 0x00 0x00 0x00 0x80 0x80 500uADC 0x00 0x00 0x00 0x17 0x8B 0x35 0x11 0x00 0x55 0x31 0x00 0x00 0x00 0x00 0x00 0x00 0x80 0x80 5AAC 0x00 0x52 0xDD 0x07 0x03 0x00 0x13 0x80 0x25 0x11 0xF8 0x00 0x00 0x00 0x00 0x00 0x90 0x80 500mAAC 0x00 0x92 0xDD 0x07 0x03 0x52 0x10 0x80 0x25 0x11 0xF8 0x00 0x00 0x00 0x00 0x00 0x90 0x80 50mAAC 0x00 0x52 0xDD 0x07 0x03 0x00 0x13 0x80 0x25 0x11 0xF8 0x00 0x00 0x00 0x00 0x00 0x90 0x80 5mAAC 0x00 0x92 0xDD 0x07 0x03 0x52 0x10 0x80 0x25 0x11 0xF8 0x00 0x00 0x00 0x00 0x00 0x90 0x80 500uAAC 0x00 0x52 0xDD 0x07 0x03 0x00 0x13 0x80 0x25 0x11 0xF8 0x00 0x00 0x00 0x00 0x00 0x90 0x80 Continuity 0x00 0x74 0xCF 0x17 0x83 0x35 0x10 0x00 0x55 0x00 0x00 0x00 0x00 0x0A 0x00 0x40 0x86 0x80 Diode 0x00 0xC0 0xCF 0x17 0x8B 0x8D 0x10 0x00 0x55 0x31 0x00 0x00 0x00 0x08 0x00 0x40 0x86 0x80 For more information please see the library documentation for each platform ZYNQ or Digilent Microcontroller boards. EEPROM Memory The DMM Shield is equipped with a non-volatile EEPROM memory chip from Microchip: 93LC66BT datasheet available from Microchip's website ), which has 512 bytes/256 words (4kbits) available space. The memory can be accessed over a custom SPI protocol, using digital IO pins exposed in the DMM Shield connector: CS_EEPROM (EEPROM SPI chip select), DO (SPI MISO), DI (SPI MOSI) and CLK (SPI CLK). While the chip select line is specific to EEPROM module, the SPI lines (data and clock) are shared with the DMM device. Note the data is written and read from memory using word format addressing, instead of byte: bytes 0-1 are written at address 0x00, bytes 2-3 are written at address 0x01, etc. The EEPROM is used to store the following system information: Section Content Addresses (words) Size Factory calibration data 0x93 - 0xFF 109 words / 218 bytes Serial Number 0x8C - 0x92 7 words / 14 bytes User calibration data 0x1F - 0x8B 109 words / 218 bytes Free Memory 0x00 - 0x1E 31 words / 62 bytes Please consult the DMM Shield Library User Guide for more information about the EEPROM module usage and communication. For more details about Calibration process, read more on Calibration Procedure below. Measurement Scales DMM Shield comes with preset scales of measurement. They will indicate the maximum value that can be accurately measured with the device. Keep in mind that at low values the resolution is lower and different scales might give a more accurate result since the device is calibrated closer that value. Ex: for a 40k resistor is better to use the 50k scale instead of the 500k for a better resolution. There are 4 scales for voltages, 5 for current and 7 for resistances. Additionally, there are two extra scales for Diode and Continuity. Scales - - - - - - - - AC Voltage 50m 500m 5 30 - - - V DC Voltage 50m 500m 5 50 - - - V AC/DC Current 500u 5m 50m 500m 5 - - A Resistances 50 500 5k 50k 500k 5M 50M Diode Continuity The device comes factory calibrated for each scale. For more details about calibration please see the Calibration procedure below. Accuracy The accuracy of the DMM Shield is around 0.1% for AC/DC Currents and Voltages, 500-5M Resistances and within the scales; 1% for 50 and 50M Resistances. For AC Current and Voltage we guarantee the 0.1% accuracy at 50/60Hz. Note that outrunning the end of a scale will increase the measurement error. The accuracy is computed in percentage as a difference between the reference value and the measured value, reported to full scale. Let's consider RF , M F as the reference and the measured value at full scale and FS the full scale. The accuracy is computed as follows: Accuracy = RF - M F 100 FS (10) Calibration Procedure The DMMShield needs calibration before performing measurements and delivering correctly measured values to the user. This is due to errors introduced by the chip itself and on-board additional electronics. Calibration is the process of computing and applying correction coefficients to the measured values that allow precise measurements. The process consists of computing an additive and a multiplicative coefficient for each scale. Calibration is done by collecting pairs of reference value and measured value (RefVal, MsVal) in multiple points. The reference value is the value measured with an accurate instrument, considered to be the actual value to be measured by the DMMShield device. The measured value is the value reported by DMMShield hardware. When all these pairs are collected, the calibration coefficients are computed mainly using the difference between the reference and the measured values. Depending on the scale, different types of calibration are performed, as detailed in the following chapters: 2 Points Calibration for Resistance Scales This method applies to the Resistance scales. It collects the pairs (RefVal, MsVal) in two points: 0 point (short between probes), and full scale value. Let's consider this pairs as being (R0 , M 0 ) and (RF , M F ). The calibration coefficients are computed in the following manner: CalibM U LT = R0 - RF -1 M0 - MF C alibADD = (R0 - M 0)(1 + CalibM U LT ) The reference value for the short is considered to be 0: R0 = 0 (1) (2) The calibration coefficients are applied to the acquired value in the following manner: V alue corrected = (1 + C alibM U LT )V alue acquired + C alibADD (3) 3 Points Calibration for DC This method applies to the DC Voltage and DC Current scales. It collects the pairs (RefVal, MsVal) in three points: 0 point (short between probes for voltage and open for current), negative full scale value and positive full scale value. For example, for VoltageDC500m scale, the following points are used: 0 point (short between probes), -500mV, 500 mV. Let's consider this pairs as being (R0 , M 0 ), (RF N , M F N ) and (RF P , M F P ). The calibration coefficients are computed in the following manner: CalibM U LT = RF P - RF N -1 MF P - MF N (4) C alibADD = (R0 - M 0)(1 + CalibM U LT ) (5) The reference value for the zero calibration is considered to be 0: R0 = 0 The calibration coefficients are applied to the acquired value in the following manner: V alue corrected = (1 + C alibM U LT )V alue acquired + C alibADD (6) 2 Points Calibration for AC This method applies to the AC Voltage and AC Current scales. It collects the pairs (RefVal, MsVal) in two points: 0 point (short between probes for voltage and open for current) and full scale value. For example, for VoltageAC500m scale, the following points are used: 0 point (short between probes) and 500 mV. Let's consider this pairs as being (R0 , M 0 ), (RF , M F ). The calibration coefficients are computed in the following manner: CalibM U LT = RF MF 2 - M02 -1 (7) C alibADD = M 0 (8) The reference value for the zero calibration is considered to be 0: R0 = 0 The calibration coefficients are applied to the acquired value in the following manner: V alue corrected = (1 + C alibM U LT )|V alue acquired 2 - C alibADD 2| (9) Software Libraries Digilent provides libraries to access DMM Shield functionality. The libraries were created to support ZYNQ plaform and Digilent PIC32 microcontroller boards. Both libraries come with a demo that allows the communication with the DMM Shield through UART. Functions as setting a scale and measure can be accessed by entering commands in the UART terminal emulator. Another demo shows how to access the memory left in the EEPROM by reading and writing 32 words. Documentation and downloads for these libraries can be found at the following locations: ZYNQ PIC32 Appendix: Pinout Tables DMM Shield Connector Pinout Banana Connector Interface J1 J2 J3 J4 Voltage/ COM Current (mA) Current (A) Power Connector J9 Connector pin number Arduino Shield Name 1 NC 2 3V3 3 NC 4 3V3 5 5V0 6 GND 7 GND 8 VIN Analog Connector J6 Bottom Row Top Row Connector pin number Arduino Shield Name Connector pin number Arduino Shield Name 1 A0 2 A6 3 A1 4 A7 5 A2 6 A8 7 A3 8 A9 9 A4 10 A10 11 A5 12 A11 Digital IO Connector J7 Bottom Row Top row Connector pin number Arduino Shield Name Connector pin number Arduino Shield Name 1 IO41 2 A 3 IO40 4 G 5 IO39 6 IO13/CLK 7 IO38 8 IO12/DI 9 IO37 10 IO11/DO 11 IO36 12 IO10/CS_DMM 13 IO35 14 IO9/CS_EEPROM 15 IO34 16 IO8 J8 Bottom Row Top Row Connector pin number Arduino Shield Name Connector pin number Arduino Shield Name 1 IO33 2 IO7 3 IO32 4 IO6 5 IO31 6 IO5 7 IO30 8 IO4/RLD 9 IO29 10 IO3/RLU 11 IO28 12 IO2/RLI 13 IO27 14 IO1 15 IO26 16 IO0 About this Document This reference manual applies to Revision C of the DMM Shield. Additional Information Arduino DMM Shield Library User Guide Arty Z7 DMM Shield Oled Demo User Guide Arty Z7-20 DMM Shield Webserver Demo User Guide PIC32 DMM Shield Library User Guide Zynq DMM Shield Library User Guide doc, rm, dmmshield ucrie to our Newletter First Name Last Name Email Address Our Partner Help Cutomer Info Compan Info Xilinx University Program Technology Partners Distributors Technical Support Forum Reference Wiki Contact Us Videos FAQ Store Info About Us Shipping & Returns Legal Jobs Internships Submit Connect With U