Hi everyone,
I have a few questions relating to my project, but first of all a little background.
I am making an optical absolute position encoder. It is 8-bit (i.e. 8 IR LED emitters and 8 corresponding phototransistor recievers) and the disk is gray code. The aim is to measure average wind direction and output the info on a small LCD. So the shaft will be rotating at low speeds but with jittery directional changes. It also has to be of low power consumption, continuouly operating for a few days running, about 3 days. The source of the power for now is a quality 9V battery, as it has to be portable, but im open to any other suggestions.
The sensor circuit setup has tested fine so far (although i have not actually put all 8 in action with the code wheel yet). I originally assumed I would need a schmitt trigger to ensure a clean, reliable digital signal (to send to the microcontroller), however the image below shows that perhaps the 7414 hex schmitt IC is not required? In the image below, the blue waveform is without the 7414 hex inverter, and the yellow is the conditioned signal outputted from the 7414 hex schmitt IC.
Would I be best off keeping the 7414 IC in place? or would leaving it out offer me a saving in power consumption (for 8 sensors I would need two 7414 IC's)?
The next question is selection of the microcontroller. Perhaps 4 years ago I breifly used a PIC18F452 microcontroller in a group project, and so although im not totally inexperienced I am a little rusty in my microcontroller knowledge
I'm taking over this project from a previous student (a total rebuild with the aim of improvemnt, but certain ideas will be reused) and they used a MSP430 low power microcontroller from texas instruments. This is a 3.3V microcontroller, and to me it seems a pain to bother with voltage supply translation IC's (three 74LVX3245 were used in the previous project) in an other wise simple elegant piece of hardware. Would the benefits of a low power MCU be lost with all this mucking around with level translating IC's and the need to power them. Basically the signal will go from 5v for sensor circuit....then 3.3V for input to the MCU....then back to 5v for LCD panel!
I figure simple design with an appropriate 5V MCU will be fine to run for a few days yes/no?
What to people here think about this and suggest for an MCU?
In general in which areas of design should i be careful/aware of to avoid careless power consumption?
I have probably missed out some information required to answer these questions accurately and I am happy to give any extra info required. The LCD panel used in the old project was a MC1602C-SYR but I havent given this any thought in terms of improvement or upgrade.
Many thanks in advance for any knowledgeable help
I have a few questions relating to my project, but first of all a little background.
I am making an optical absolute position encoder. It is 8-bit (i.e. 8 IR LED emitters and 8 corresponding phototransistor recievers) and the disk is gray code. The aim is to measure average wind direction and output the info on a small LCD. So the shaft will be rotating at low speeds but with jittery directional changes. It also has to be of low power consumption, continuouly operating for a few days running, about 3 days. The source of the power for now is a quality 9V battery, as it has to be portable, but im open to any other suggestions.
The sensor circuit setup has tested fine so far (although i have not actually put all 8 in action with the code wheel yet). I originally assumed I would need a schmitt trigger to ensure a clean, reliable digital signal (to send to the microcontroller), however the image below shows that perhaps the 7414 hex schmitt IC is not required? In the image below, the blue waveform is without the 7414 hex inverter, and the yellow is the conditioned signal outputted from the 7414 hex schmitt IC.
Would I be best off keeping the 7414 IC in place? or would leaving it out offer me a saving in power consumption (for 8 sensors I would need two 7414 IC's)?
The next question is selection of the microcontroller. Perhaps 4 years ago I breifly used a PIC18F452 microcontroller in a group project, and so although im not totally inexperienced I am a little rusty in my microcontroller knowledge
I'm taking over this project from a previous student (a total rebuild with the aim of improvemnt, but certain ideas will be reused) and they used a MSP430 low power microcontroller from texas instruments. This is a 3.3V microcontroller, and to me it seems a pain to bother with voltage supply translation IC's (three 74LVX3245 were used in the previous project) in an other wise simple elegant piece of hardware. Would the benefits of a low power MCU be lost with all this mucking around with level translating IC's and the need to power them. Basically the signal will go from 5v for sensor circuit....then 3.3V for input to the MCU....then back to 5v for LCD panel!
I figure simple design with an appropriate 5V MCU will be fine to run for a few days yes/no?
What to people here think about this and suggest for an MCU?
In general in which areas of design should i be careful/aware of to avoid careless power consumption?
I have probably missed out some information required to answer these questions accurately and I am happy to give any extra info required. The LCD panel used in the old project was a MC1602C-SYR but I havent given this any thought in terms of improvement or upgrade.
Many thanks in advance for any knowledgeable help