ZIO, Motherboard - Zilogic Systems
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1. eB PWM O d GND PWM Port One Bit DAC An analog output can be generated from the PWM signal using a low pass filter circuit The low pass filter circuit with an op amp buffer is shown in the following diagram PWM Port If the analog output has a frequency of F the PWM frequency should be much higher than F The values of R and C are given by the following formula For an output frequency of 1kHz choosing R 4kohm C 0 04uF DC Motor Control A DC motor s speed and direction of rotation can be controlled using the PWM port The DC motor has to be interfaced through a circuit called the H Bridge A simple H Bridge constructed using switches is shown in the following diagram By controlling the switches the motor can be made to rotate forward reverse brake and free run The various switch states and their effect on the motor is shown in the following table Zilogic Systems Page 13 ZIO Motherboard User Manual Rev 0 1 Vcc Vcc a Free Running State b Reverse State Vcc Vcc c Forward State d Brake State S1 S2 3 S4 Function 0 0 0 0 Free run 0 1 1 0 Reverse 1 0 0 1 Forward 0 1 0 1 Brake 1 0 1 0 Brake Forward The current to flows in one direction through the motor Reverse The current flows in the opposite direction through the motor Brake Applying same voltage to both the terminals counters the back EMF produced by the motor and causes it to come to a sudden stop Free run Power is cut off from the motor and th2. button Zilogic Systems Page 17 ZIO Motherboard User Manual Rev 0 1 Appendix A Port Pin Mapping The API deals with subsystems in the board called modules The modules available in the API are 1 GPIO 2 IC 3 Sensor 4 PWM Each module controls a set of pins These pins are terminated in the pins of various ports An example with GPIO module is shown in the following diagram GPIO Port 0 Output O Output 1 GPIO Module GPIO Port 1 Output O Output 1 The API always deals with modules and its pins So to control a pin on a particular port it is required to know which pin on the module it is mapped to Table A 1 Port GPIO 0 Signal Module Pin Output 0 GPIO Output 1 GPIO Input O GPIO Input 1 GPIO a Table A 2 Port GPIO 1 Signal Module Pi in Output 0 GPIO 2 Output 1 GPIO 3 Input O GPIO 2 Input 1 GPIO 3 Table A 3 Port I2C 0 Signal Module Pin SDA DC SCL DC Interrupt GPIO 4 Zilogic Systems Page 18 ZIO Motherboard User Manual Table A 4 Signal SDA SCL Interrupt Table A 5 Signal SDA SCL Interrupt Table A 6 Signal SDA SCL Sensor 0 Sensor 1 Table A 7 Signal SDA SCL Sensor 0 Sensor 1 Table A 8 Signal SDA SCL Sensor 0 Sensor 1 Table A 9 Signal SDA SCL Sensor 0 Sensor 1 Table A 10 Port PWM 0 Signal PWM 0 PWM 1 Port I2C 1 Module Pin DC DC GPIO 4 Port I2C 2 Module Pin DC DC GPIO 4 Port AIN
3. of a rectangular waveform The PWM signal can be used to control the power delivered to a load by controlling the duty cycle of the PWM signal PWM signals are generally used for Motor speed control LED brightness control power supplies and wave form generation The PWM signal is a CMOS TTL output The signal has a series resistor of 180 ohm FIXME to protect against accidental shorting to GND Zilogic Systems Page 5 ZIO Motherboard User Manual Rev 0 1 Figure 2 5 PWM signals with various pulse widths Duty Cycle 20 Duty Cycle 60 Phase A B Pin4 5 These are digital input signals to be driven by the two outputs of a quadrature encoder This can be used to determine the speed and direction of rotation of the shaft to which encoder is attached This is generally used to determine the speed and direction of the motor controlled by the PWM signal The Phase signal is a CMOS TTL input The signal is pulled up to 5V through a 10K resistor GND Pin 6 This is the ground signal All other signals are referenced to this signal Figure 2 6 PWM Port 5V Pin 1 GND Pin 6 180 ohm PWM O Pin 2 180 ohm PWM PWM 1 Pin 3 Phase A Pin 4 Quadrature Encoder Phase B Pin 5 Interface Zilogic Systems Page 6 ZIO Motherboard User Manual Rev 0 1 Chapter 3 ZIO Recipies 1 GPIO Port Connecting LEDs Connect the anode of the LED to an Output signal and the cathode to GND The built in series resistor is su
4. 0O Module Pin DC DC Sensor 0 Sensor 1 Port AIN 1 Module Pin DC DC Sensor 2 Sensor 3 Port AIN 2 Module Pin DC DC Sensor 4 Sensor 5 Port AIN 3 Module Pin DC DC Sensor 6 Sensor 7 Module Pin PWM 0 PWM 1 Zilogic Systems Rev 0 1 Page 19
5. 0V AC In such situations the microcontroller needs to be electrically isolated from the high voltage section using a opto coupler Note that though relays can also be used for this purpose they are generally bulky slow unreliable and power hungry Isolated Subsystem Optocoupler Output O GND GPIO Port Connecting to CMOS TTL inputs CMOS TTL inputs can be directly connected to the Output signal An example of shift register connected to the Output signals is shown in the following circuit diagram DO D1 D2 D3 e CMOS TTL vere Shift Register Output 1 D4 D5 D6 D7 GPIO Port Connecting Switches Switches can be directly connected between the Input and GND When the switch is pressed the Input signal will be low and when the switch is released the Input signal will be become high due to the built in in pull up resistor GPIO Port Detecting External Voltage Any external voltage input can be connected to the ZIO Input signal through a MOSFET or a BJT An example circuit using a MOSFET is shown below Zilogic Systems Page 8 ZIO Motherboard User Manual Rev 0 1 GPIO Port If the input voltage Vs is greater than the threshold voltage of the MOSFET the Input signal will be low or else it will be high An example circuit using a BUT is shown below GPIO Port If the input current ls is greater than h 0 5mA hee the Input signal will be low or else it will be high For al
6. 3 0 OxFFFF 0 1 5 Ox7FFF 15 0 0 A 3 3 Non resistive Sensors Transistor Buffer Non resistive sensors usually generate a voltage signal that varies with the parameter being measured Such sensors cannot be directly connected to the Sensor N signal due the signal being pulled up to 3V using a 10K resistor A transistor buffer can be used to overcome this problem The transistor isolates the sensor from the pull up A transistor buffer circuit is shown below Sensor 0 Sensor Port Zilogic Systems Page 12 ZIO Motherboard User Manual Rev 0 1 This is a PNP emitter follower where the emitter voltage is almost equal to the base voltage For a V range of 0 to 4 4V the voltage at Sensor 0 Is Vi 0 6 To compensate for the added 0 6V subtract 0 6 to the obtained voltage Temperature Sensor The LM35 is an example of an non resistive sensor The LM35 produces a voltage that is propotional to the temperature The voltage output by the LM35 increases by 10mV for every degree Celcius rise in temperature As the temperature changes from 2 C to 150 C the voltage rises from OV to 1 5V The LM35 can be connected to the Sensor port using the transistor buffer and is shown in the following circuit 5V Sensor 0 LM35 Sensor Port 4 PWM Port LED Brightness Control An LED can be connected between the PWM N signal and GND as shown in the following diagram When the duty cycle is varied the LED brightness varies accordingly
7. M Stop Sensor U zc Sensor 1 Device Address sensor 2 i 0x42 0x43 Sensor 3 Sensor 4 LA ke G kb a zl Sensor 5 Sensor 6 3 OxFo Write Sensor 7 i H KR Read 1 Controlling GPIO Outputs The GPIO outputs can be controlled by toggling the check box on the Digital Out panel 2 Reading GPIO Inputs The GPIO inputs can be read by inspecting the check box on the Digital In panel 3 Reading Sensor Inputs The Sensor inputs can be read by inspecting the progress bar on the Sensor panel 4 Controlling PWM Outputs PWM signals can generated using the controls in the PwM panel 1 Select the PWM channels by toggling the checkboxes 2 Set the PWM frequency in the frequency slider 3 Set the PWM duty cycle in the duty cycle slider 4 Click Start to start generating PWM signal 5 Click Stop to stop generating PWM signal 5 Controlling 12C Devices DC devices can be accessed using the controls in 12C panel To list devices present on the bus Zilogic Systems Page 16 ZIO Motherboard User Manual Rev 0 1 1 Click on the Scan button 2 Address of devices present is displayed on the list box To write to a device 1 Select the device address 2 Enter the data bytes to be written in hex separated by commas in the Write text box 3 Click on the Write button To read from a device 1 Select the device address 2 Select the no of bytes to read 3 Click on the Read
8. ZIO Motherboard User Manual 0 1 November 2009 ZIO Motherboard User Manual Rev 0 1 ZIO Motherboard User Manual Rev 0 1 Table of Contents BN Iddee GUN NN WEE 1 Le PUAN SONNY EE 1 Eeler EE 1 2 e ue dire 1O 4 E 2 TORPO dE 2 eg TG PO geed 3 SE eg Ge EE 4 e BN e DA e EE 5 Sale e E 7 TORD FO EE 7 E Ke PO ea A E E E ee eee 9 Be IIS Ol PON E 10 A PANN Ge EE 13 4 LIO Control Panel E 16 Ke eieiei GPIO QUT UNS sasirnane AEE ADERARE EEDE ARES ENDE 16 2 Reading GPIO Wl e 16 2 Reading EENEG ee 16 4 Controlling PWM Outputs ccccceccecceeceeceeceeseseeseeceecaeeeesaeseseeseeseesaesaesaesaeseeseesaees 16 5 COMMOMING A20 RE 16 AFROT Sc E ee e WEE 18 Zilogic Systems Page iii ZIO Motherboard User Manual Rev 0 1 Chapter 1 Introduction 1 Philosophy e Move development from micro controllers to PC e Use high level languages like Python and Java e Extend the IO capabilities of the PC e Rapid prototype development 2 Product Features e Connects to PC through USB e Interfaces 2C Sensor Input GPIO PWM Output Host ode API for programming the ports e APIs available for Java and Python e API documentation for easy reference e Port interfacing guidelines for common scenarios e GUI based Control Panel to explore the board e On field firmware upgrade through USB Figure 1 1 Block Diagram GPIO GPIO Port 1 Port 0 USB I2C I2C I2C 8 Serial Port 0 Port 1 Po
9. dingly and the raw value N produced is given by the following formula N OxFFFF x R R 10K Here e Ris the resistance of the sensor e 10K is the internal pull up resistor on the Sensor signal For more details refer Section 3 Sensor Port An example circuit using the LDR is shown below Sensor 0 d GND Sensor Port 3 2 Voltage Sensors Voltage measurement 3V to 3V Though the ADC input range is 0 to 3V it is possible to measure voltages between 3V and 3V using a simple circuit The circuit diagram is shown in the figure below Sensor 0 Sensor Port To better understand the operation of the circuit the circuit is shown with the internal pull up resistor on the Sensor signal in the following diagram Zilogic Systems Page 11 ZIO Motherboard User Manual Rev 0 1 3V Sensor 0 GND Using superposition the voltage at Sensor 0 is given by the following formula Voltage at Sensor 0 1 5V Vi 2 As V decreases from 3V to 3V the voltage at the Sensor 0 decreases linearly from 3V to OV and the raw value from OxFFFF to 0 Vi V Voltage at Sensor 0 V Raw Value 3 3 OxFFFF 0 1 5 Ox7FFF 3 0 0 Voltage measurement 15V to 15V The following circuit can be used to measure voltages in the range 15V to 15V The input voltages and the corresponding raw values is shown in the table below Sensor 0 Sensor Port Vi V Voltage at Sensor 0 V Raw Value 15
10. e motor free runs and eventually stops To control the motor through digital signals the switches are replaced by transistors MOSFETs Driver ICs like the L298 that implement the H Bridge can also be used for motor control applications The block diagram of one half of a L298 is shown in the following diagram Zilogic Systems Page 14 ZIO Motherboard User Manual Vs Rev 0 1 GND By controlling the inputs various functions can be selected as shown in the table below In In2 Function A Brake 0 0 1 1 0 1 1 Brake Reverse Forward When in Forward state or Reverse state the speed of the motor can be controlled by driving the inputs with a PWM signal In1 Duty Cyle 0 100 0 100 0 X In2 Duty Cycle 0 100 100 0 X 0 Function Brake Brake Reverse full speed Forward full soeed Reverse speed propotional to duty cycle Forward speed propotional to duty cycle A circuit for interfacing a DC motor to the PWM port using the L298 is shown in the following diagram PWM Port Zilogic Systems Page 15 ZIO Motherboard User Manual Rev 0 1 Chapter A ZIO Control Panel The ZIO Control Panel is a GUI application that allows most features of ZIO to be tested without writing code Figure 4 1 Control Panel Screenshot 710 Control Panel Digital In PWM J MMM o 0 We 3 4 O 1l LOOO00 Digital Out Freq kHz L L a 2 a Duty sensor gt Start
11. fficient to limit the current Output 0 LED a GND GPIO Port Connecting series of LEDs Since the Out put signal can not provide sufficient power for more than one LED and external power source is to be used And the power supply can be controlled using a MOSFET switch LEDs Z ht kt M 470 ohm Output O GND GPIO Port The circuit diagram for connecting a series of LEDs is shown above The following formula can be used to calculate the resistance for the current limiting resistor The voltage drop across the MOSFET is considered to be negligible R Vec NVa Ig Where Vg Voltage Drop Across LED N No of LEDs lg Current for the required brightness Vog LED supply voltage R Current Limiting Resistor As an example for the following parameters e V 12V K lg 11mA e N 4 the calulated current limiting resistance is 470 ohms Connecting relays Relays are used to control a high voltage high currect circuit with a low voltage low current signal A relay can be connected to the ZIO through a MOSFET as shown in the following circuit diagram Zilogic Systems Page 7 ZIO Motherboard User Manual Rev 0 1 Output O GND GPIO Port Isolating outputs using opto coupler There are situations in which signals from one subsystem need to be electrically isolated from another subsystem in an electrical equipment For example a microcontroller operating at 5V controls the power to a load operating at 23
12. ic Systems Page 2 ZIO Motherboard User Manual Rev 0 1 Figure 2 2 GPIO Port 5V Pin 1 GND Pin 6 180 ohm Output O Pin 2 180 ohm Output 1 Pin 3 Input O Pin 4 Input 1 Pin 5 2 12C Port The ZIO has three I2C ports marked as 12C 0 I2C 1 and 12c 2 The signals on a 12C port are shown in the following table Table 2 2 Sensor Port Signals Pin No Signal 1 5V Power 2 SCL 3 SDA 4 Reserved 5 Interrupt 6 GND 5V Power Pin 1 This is the power supply for the external devices The supply has a total current limit of 200mA SCL SDA Pin 2 3 These are 12C bus signals and can be used to connect DC devices Any 5V tolerant I2C device can be connected to the bus Interrupt Pin 5 This is a digital input signal This is a shared signal for all 12C devices and should be driven by open collector outputs The signal is pulled up to 5V through a 10K resistor GND Pin 6 This is the ground signal All other signals are referenced to this signal Zilogic Systems Page 3 ZIO Motherboard User Manual Rev 0 1 Figure 2 3 12C Port 5V Pin 1 GND Pin 6 SCL Pin 2 GC SDA Pin 3 Master Interrupt Pin 5 3 Sensor Port The ZIO has four sensor ports marked as AIN 0 AIN 1 AIN 2 and AIN 3 The signals on a sensor port are shown in the following table Table 2 3 Sensor Port Signals Pin No Signal 1 5V Power 2 GCL 3 SDA 4 Sensor 0 5 Sensor 1 6 GND 5V Power P
13. in 1 This is the power supply for the external sensors The supply has a total current limit of 200mA SCL SDA Pin 2 3 These are I2C bus signals and can be used to connect DC devices Any 5V tolerant I2C device can be connected to the bus Sensor 0 1 Pin 4 5 These are analog input signals The signals are connected to a 10 bit ADC The input signal range is 0 to 3V The input is translated to a value in the range 0 to 1023 by the ADC The pins are connected to a 3V reference through 10K pull up resistors GND Pin 6 This is the ground signal All other signals are referenced to this signal Zilogic Systems Page 4 ZIO Motherboard User Manual Rev 0 1 Figure 2 4 Sensor Port 5V Pin 1 5V 5V GND Pin 6 SCL Pin 2 I2C Master SDA Pin 3 Sensor O Pin 4 Sensor 1 Pin 5 4 PWM Port The ZIO has one PWM port marked as PwM 0 The signals on a PWM port are shown in the following table Table 2 4 Sensor Port Signals Pin No Signal 5V Power PWM OU PWM 1 Phase A Phase B GND Ooo KRW N A 5V Power Pin 1 This is the power supply for the external sensors The supply has a total current limit of 200mA PWM 0 1 Pin 2 3 These are PWM output signals The PWM signal when active produces a stream of pulses whose width can be controlled through software An important parameter of a PWM signal is the duty cycle The duty cycle is defined as the ratio between the pulse duration and pulse period
14. l practical purposes a 1mA input current is sufficient to make the Input signal go low The base resistance R has to be chosen to make the Input signal low when the required input voltage is driven Rb Vs Vbe h Connecting an Analog Comparator An analog comparator can be used to identify if the input voltage is larger than a specified reference voltage Any operational amplifier can be used as a comparator but a dedicated comparators like LM339 which provide open collector CMOS TTL outputs are suitable for interfacing with logic circuits An example circuit is shown in the following diagram LM339 GPIO Port Isolating inputs using opto coupler As in the case of outputs inputs can also be electrically isolated using opto couplers Isolated Subsystem Input O Optocoupler GPIO Port 2 12C Port Connecting 5V I2C devices Since the I2C signal are pulled up to 5V 5V 12C devices can be directly connected to the I2C port Zilogic Systems Page 9 ZIO Motherboard User Manual Rev 0 1 I2C Device I2C Port Connecting 3 3V DC devices with 5V tolerance Any 3 3V I2C device with 5V tolerance can be directly connected to the I2C port The device can be powered from an external 3 3V supply or the 3 3V supply can be generated from the 5V Power using a regulator An example ciruit with the commonly available LM1117 3 3 regulator is shown below LM1117 3 3 3 3V I2C Device I2C Port IO Ex
15. pander Additional digital inputs and outputs if required can be obtained using a I2C IO expander The PCA8574 provides 8 digitial I O lines and PCA8578 provides 16 digital I O lines An example circuit using the PCA8574 with I2C device address set to 0x20 is shown below PO Pl P2 P3 5 2C IO Expander PCAS5S 4 SDA ADO Interrupt jet GND P4 P5 P6 P7 l2 C Port 3 Sensor Port 3 1 Resistive Sensors Connecting a Potentiometer The position of potentiometer can be sensed by connecting the potentiometer to the sensor input as shown in the figure below When the center pin 2 of the potentiometer is moved from pin 1 to pin 3 the raw value varies from 0 to Nmax Where Nmax IS given by the following formula Nmax OXFFFF x Rmax Rmax 10K Here e Rmax is the maximum resistance of the potentiometer Zilogic Systems Page 10 ZIO Motherboard User Manual Rev 0 1 e 10K is the internal pull up resistor on the Sensor signal For more details refer Section 3 Sensor Port For a 10K potentiometer Nmax OXFFFF x 10K 10K 10K Ox7FFF sensor 0 1 GND sensor Port Connecting a Resistive Sensor Sensors whose resistance varies with the parameter being measured are called resistive sensors Examples of resistive sensors are Light Dependent Resistor LDR thermistor etc These sensors can be directly connected between the Sensor signal and GND As the parameter being measured varies the resistance varies accor
16. rt 2 L Host PC ZIO Motherboard Zilogic Systems Page 1 ZIO Motherboard User Manual Rev 0 1 Chapter 2 Connecting to ZIO In this chapter we will describe the connector used for the ZIO ports and the pins found on each of the ports The ZIO has 4 different types of ports 1 GPIO Port 2 12C Port 3 Sensor Port Marked as AIN on the ZIO 4 PWM Port All the ports are available through RJ12 jacks The RJ12 is similar to RJ11 but has six pins The RJ12 jack pins and pin numbering are shown in the following diagram Figure 2 1 RJ12 Jack 1 2 3 4 5 6 1 GPIO Port The ZIO has two GPIO ports marked as GPIO 0 and GPIO 1 The signals on a GPIO port are shown in the following table Table 2 1 GPIO Port Signals Pin No Signal 1 5V Power 2 Output 0 3 Output 4 Input 0 5 Tnap e 1 6 GND 5V Power Pin 1 This is the power supply for the external device The supply has a total current limit of 200mA Output 0 1 Pin 2 3 These are digital output signals The signal is a 5V logic signal but the output can drive a 5V device or 3 3V device with 5V tolerance The output signal has a series resistor of 180 ohm FIXME to protect against accidental shorting to GND Input 0 1 Pin 2 3 These are digital input signals The signal is a 5V logic signal The signal is pulled up to 5V through a 10K resistor GND Pin 6 This is the ground signal All other signals are referenced to the this signal Zilog
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