CAPSENSE™ & MagSense Forum Discussions
I made a average current measurement while the mcu is sleeping and the result was:
Peak to peak: 2.57mA / Average: 783µA / Standard Dev: 873µA / Max: 2.79mA / Min 216µA
I got a lot of spikes in the current graph.
To my set up:
Source voltage: 3.3V
All 10 sensor are enabled. The second as guard
I set him to sleep in the register CTRL_CMD(0x86) whit the CMD_OP_CODE 7.
How can I reduce the average current dramatically and why get I such high spikes?Show Less
I am working on oil level measurement application. where we will going to measure the oil of tank. I have seen the demo video of this kit that how you have measured the water level by using capsense.
There're few question in my mind after seeing video. that i will mention below.
Q.1. Will it measure the level of oil in metal tank . Approximate dimension of this tank is 2 cm. what are material will impact on the capsense touch.
Q.2. You have used flexible strip for sensing the level. but we are planning to do it with solid metal strip that won't be flexible. so is it possible to convert it into metal strip?.
Q.3.It is con tactless flexible strip that stick on outside of bottal. but we want to insert that strip into oil tank, so question is, what are hurdles will comes if it will comes in contact with Oil?.
Q.4.In video,The flexible strip height and width is too small. if we want to customize our own cap-sense strip. How much height we can go with. and want small width of that strip, so how much minimum width we can implement.
so this are few question that i have mentioned above. please reply me back as soon as possible.
waiting of your valuable response.
Thanks in advance
I checked HW is ok, Vcc is stable and outputs 18.8V, Vdd is 3.3V, I2C speed is lower than 100kHz, all timings are checked and OK, no line crossing. Pin 12 CS2/GUARD that also works as AXRES is +3.3V. Still after 0x2FFF trials, no ACK. Any idea?
Schematic is attached.Show Less
According to AN64846 ,a salty water by dissolving 40 gm of cooking salt (NaCl) in 1 liter of water , is a proper simulation of worst-case condition.
What is parasitic capacitance value of this kind salty water?
why not the saturated salty water to be the worst-case?Show Less
Capacitive sensing can be overwhelming for a newcomer. The nature of the underlying electromagnetic phenomena is complex. That’s why many newcomers tend to cut corners. They tend to skip the part of understanding the physics involved and jump head-first to projects. Naturally, they soon feel lost and resort to trial and error.
This chapter contains all the knowledge we wish we had when we first started working on capacitive sensing. It will teach you the basics of electrostatics, conductors, and capacitance tailored to the need of a capacitive touch sensor designer.
Then you’ll familiarize yourself with one of the most useful concepts in capacitive sensing: the fundamental case of the parallel plate capacitor. Understanding this case can help you unlock the mysteries of capacitive sensing!
Finally, you’ll get an intuitive understanding of how certain parameters, like electrode geometry, dielectrics, and traces affects the performance of a capacitive touch sensor.
Thanks to Benjamin Franklin’s pioneering experiments, that took place almost three centuries ago, almost everyone knows today that electric charges can travel through materials causing flow of electric current.
The tendency of a material to allow the flow of electric current through its body is described by conductivity, σ. On the contrary, the difficulty that a material poses to electric charge conduction can be quantified by resistivity, ρ.
You can read and learn more about the fundamentals of electrostatics & capacitance for capacitive touch sensors here.
From <<Cypress’ CapSense Sigma-Delta Algorithm>>,we know CY8C21x34 has a special CSD structure with a bleed resistor. and it works very interesting
as the document says.
Now according to AN64846, PSOC 4S series has a fouth-generation capsense. it is called CSD_V2,isn't it? there is no bleed resistor. i don't know how it works . who can tell something about it?
And is capsense in CY8C21x34 the third generation capsense, with the CSD_V1 structure?
Rotary Encoders are another use case for inductive sensing. This section discusses the design of inductive rotary encoder. The construction of rotary encoder involves two sensor coils and N number of targets placed on the rotating platform as shown in the figure below.
Construction of Inductive Rotary Encoder
The number of targets (N) decides the angular resolution as shown in:
Angular resolution = 360/(N*4)
The sensor coils need to be separated at an angle twice the angular resolution. For example, if the number of targets N = 8, then the achievable angular resolution is 11.25° and the required spacing between sensor coils is 22.5°. The direction of rotation can be determined using the previous value of coil ‘A’ and the current value of coil ‘B’ as shown in Table 2. If the current value of coil ‘B’ and previous value of coil ‘A’ are same, it means the direction of rotation is anti-clockwise direction; if the values are different, then is the direction of rotation is clockwise.
Direction of Rotation
To find out more on MoT designs, please see the Inductive Sensing Design Guide.