In this topic, we are going to explore a voice recording and playback module using ISD1760 IC. It has distinguished features of being multi-message, single-chip, high quality, and fully integrated device. It is suitable for a wide range of electronics applications regarding voice recording and playing back.
Depending upon the particular device the message duration can be selected by the user from 26 seconds to 120 seconds. Another interesting feature is that by using an external resistor sampling frequency can also be adjusted in this ISD1700 series. Combining both options gives the user an interesting choice to tradeoff between the duration and quality of the recording.
In order to provide a flexible optimized range of operating voltage, this series works best from 2.4V to 5.5 V.
The following figure shows the pinout diagram of the Voice Recorder and Playback Module based on ISD1760 IC.
+5V and GND pins are used to power up the module. It can also be power up from a Connector plugin black color. A MIC is available for recording and SP+ and SP- pins are used to connect the external speaker to hear recorded voice notes.
SPI and Analog IN Pins Description
The pin configuration and their description is given below.
- VCCD = Power Supply for Module.
- LED = LED output
- RESET = When signal is present at this pin. It enters in default state.
- MISO = Master In Slave Out: When serial clock signal is present, On falling edge of clock data is shifted out
- MOSI = Master Out Slave In: On Rising edge of clock, data is latched into device.
- SCLK = Serial clock
- SS = Slave select: Through this pin a slave device is selected and SPI interface is enables.
- VSSA = Analog Ground: This pin is for ground of analog circuit.
- Analn = Analn: This pin is used for feeding analog input for recording.
- MIC+ = In case of differential microphone, it is non inverted input.
- MIC- = In case of differential microphone it is inverted input.
- VSSP2 = This pin is used as ground for –ve PWM speaker drive.
- SP- = This provides –ve terminal for class D PWM speaker.
- VCCP = This is power supply for PWM speaker.
- SP+ = This provides +ve terminal for class D PWM speaker.
- Vssp1 = This provide ground terminal for PWM speaker.
- AUD/AUX = Auxiliary output: This is used as current or voltage output.
- AGC = Automatic Gain Control: It is used to adjust the microphone preamplifier circuit gain.
- VOL = Volume = IT provide 8 levels of volume control.
- ROSC = Oscillator Resistor: To set the duration, this resistor sets the sample Frequency.
- FT = Feed Through: For output it enables feed-through path for Analn signal.
- PLAY = Playback: Used to play messages in a loop or individually.
- REC = Record: Start recording of message, when activated.
- ERASE = Erase messages individually or as a whole, when activated.
- FWD = Forward: Moves the pointer of playback to next message.
- RDY/INT = Ready/Interrupt Status Review: An open drain output.
- VSSD = Digital Ground: This pin is used as ground for digital circuit.
- Actual Module:
Descriptions of Buttons on Module
This push button is used to record the voice note (V1) in module. Press REC button and keep it pressed. LED D1 will light up and it will remain ON. Now speak in microphone on module.
When finished recording just release the REC button. LED D1 will Turn off and voice will be stored in module ISD1760. Now to record next voice note (V2) again repeat above process staring from pressing REC push button.
This push button is used to play the recorded message stored in module ISD 1760.
When PLAY button is pressed once and released (No need to keep it pressed), LED D1 will light up during playback and it will play last stored voice note. Given that speaker is attached at SP+ and SP- pins of module we can here stored voice notes.
This push button is used to toggle between stored voice notes. Let’s say we have three voice notes V1, V2, V3 with V3 being last voice note. When PLAY button is pressed LED light will light up, it will play V3 and stop there. Now when FWD button is pressed, LED light will blink and it will bring the pointer back to V1. Now if PLAY button is pressed once and released, it will play voice note V1.
If FWD is pressed during the playback of one voice note, it will skip that voice note there and start playing next voice note and when that voice note finishes it will stop there.
If FWD is pressed twice in normal state (No voice note was being played), it will skip 2 voice notes and will start playing third voice note V3, given that pointer was at the start of first voice note V1.
This push-button is used to erase a particular voice note. Let’s say we have four voice notes V1, V2, V3, V4 with V4 being the last voice note. At this place, if the ERASE button is pressed. LED D1 will blink twice and it will erase voice note V4.
Let’s say we pressed FWD key after erasing voice note V4. It will bring pointer to voice note V1. If FWD key is pressed second time it will bring pointer to voice note V2. Now if ERASE key is pressed, it will erase voice note V2 from module and now there will be only 2 voice notes in module V1 and V3.
This push button is used to increase and decrease the volume of playback voice notes. When some voice note is playing pressing VOL key repeatedly causes the volume of sound to decrease. When it reaches to minimum level and VOL key is pressed again repeatedly, it will start increasing the sound of voice note till it reaches a maximum level and this process continue until we keep pressing VOL key repeatedly.
This push button is used to reset the module in its normal state. Pressing the RESET button causes the play pointer to the start of last voice note. Once RESET key is pressed, PLAY key will play last voice note no matter at which voice note we were taken by pressing FWD key.
How to use ISD1760 Voice Recording Module
The figure below shows the schematic diagram of ISD1760 voice recorder and playback module schematic diagram. This circuit diagram becomes handy when we want to replace a faulty component from module in case of damage to any onboard component.
- Dimensions: 5.2 cm x 5.5 cm
- Operating Voltage: 5 volts
- Maximum and Minimum Recording time: 6K time 75 seconds, 8K for 60 seconds;
- Operating Frequency: 6KHZ and 8KHZ optional;
- Indication Lights
- Voice Recording
- Audio playback using microcontrollers
- Low cost sound recording Applications
ISD17xx Series ICs
The order code of the ISD700 series consists of 12 alphanumeric combinations. For Example I 17 AAA B C D E FF.
- The first alphabet represents the category of the module: I=ISD=Information Storage Device.
- Next 2 digits represents product series: 17=1700
- 3 digits AAA represents storage duration of device with following coding:
30 = 20 - 60 seconds 40 = 26 - 80 seconds 50 = 33 - 100 seconds 60 = 40 - 120 seconds 90 = 60 - 180 seconds 120 = 80 - 240 seconds 150 = 100 - 300 seconds 180 = 120 - 360 seconds 210 = 140 - 420 seconds 240 = 160 - 480 seconds
Next single digit B represents package type of device with following coding:
- X = Die (Locally manufactured and dimensions are specified by manufactured).
- E=Thin Small Outline Package
- S=Small Outline Integrated Circuit Package (Having below dimensions)
- P=Plastic Dual Inline Package (Having below dimensions)
- Next single alphabet C have following representation: Y = Lead Free
- After that, Next single alphabet D represents operating temperature range of device with following coding:
I = Industrial (-40 C to +85 C) Blank = Commercial 1. Die (0 C to +50 C) Package (0 C to +70 C)
Moreover, single alphabet E represents whether device have Tape & Reel or notwith following coding:
Blank = None R = Tape & Reel
Next 2 digits FF represents whether device have Special Features Field or not with following coding:
Blank = None 01 = vAlert
So using above information we can order a module as per our requirement for particular application.