Sometimes in microcontroller projects we would like to have sound output. This is handy when you can’t look at screen, but still need to get status messages or other info. For such tasks you can use voice synthesizer chips that are able to read text with one of robotic voices. But if your needs aren’t that high, you can go with simple wave player. Skinny Satan have shared his experiments with speech synthesis using Atmega128 microcontroller. He doesn’t do any fancy algorithms here, but rather plays low quality wave chunks to make a message.
He converts sound files in to 8-bit and 8kHz data blocks that can be stored inside MCU. Then he uses PWM output along with RC low pass filter to get voice on speaker. There can be several words stored in array where algorithm can select which ones to combine to get a sentence. You are only limited by MCU flash memory which in fact is pretty OK for simple applications.
There isn’t much open hardware medical instrumentation projects that can be considered completed and reliable. MobilECG project could pretend to be one that could compete with medical grade devices. Actually Péter, the founder of project, intended to collect decent amount of funding to get medical certification. But campaign didn’t went as planned, so he decided to make project open. Since the most of work is already done it would be sad to see project die. The decision to make it open is plausible and maybe it will completed with help of community.
MobilECG is very compact device that can measure ECG using 12 leads. The ECG signal is digitized using TI’s ADS1278 eight channel ADC. For interfacing and communication to host there are two AVR micros used – Attiny24 and ATU64. Schematic is developed using KiCAD software. Firmware isn’t complete – only minor functionality with several known bugs. Anyone with biomedical engineering knowledge will definitely see the potential of this device that can be attached to any device like PC, android or other and explore own ECG signals.
Alex had previous experience with his GPS logger, so recently he decided to build another project called GPS alerter which would send SMS when device is located in a certain area. Device also is equipped with accelerometer which allows detecting movement, so it could activate GPS module and start getting data. This helps to preserve battery life as there is no need to check coordinates while it is at same coordinates.
For this project he uses Atmega8 microcontroller which read GPS data through serial port. To send SMS messages there is an old Nokia 3210 cell phone used which is fairly easy to interface.
If you spend lots of time by computer, you notice how hard is to sit straight. Over time you lean down, slide under the table or find other position that seems to be comfortable. Well there are two theories of this thing – first of all naturally your body tries to find best position to prevent you from pains and fatigue. Anyway prolonged leaning may result in back or neck pain. So siting straight may prevent from those problems. Bu how to control yourself when you are focused in to your task. You can always feel how you are sitting. Coretech Robotics suggest simple project that may help to sit upright by reminding you all the time.
Device consists of ultarsonic sensor HC-SR04 which measures distance from your head. It is fixed to the backrest of chair at the head level. Attiny85 microcontroller monitors distance to the head and if distance increases meaning that you leaned, piezo speaker gives a signal so you could fix your position. Such solution may help you to develop a habit to sit straight as it will remind you all the time. But in other hand it also may become annoying as you can lean on purpose depending on your task you are doing. Since this is not complex and may be improved upon your needs.