[Turn] Electronic technology * Note 4 "2013-03"

Link error:fixup overflow in _vector_56. Workaround:

#pragma code_seg __near_seg non_banked is placed in front of the interrupt service program {} #pragma code_seg DEFAULT is placed after interrupt service program {}

Why do interrupt functions add: #pragma code_seg __near_seg non_banked this statement? What is this statement for?
To tell the difference between flash paging and non-paged.
Use of non-paged and paging in Flash. Paging is not visible and ppage is involved in addressing it when it is used.
1 non-paged working mechanism in Flash
Flash is a total of 128K, a page is 16K, then there should be 8 pages is, but the actual only 6 paging. There are 2 non-paged pages in 4000-7fff, and C000-FFFF two logical address Windows. Then, when the program is addressed within 64K (the 2^16=64k,16 capacity is 64K), there is no paging, directly using the two non-paged data. In fact, 3E page 3F pages are visible, but they are the 2 non-paged mappings. Therefore, using non-page flash, you do not have to set the Ppage register, directly using the logical address.
This we can see from the following:

/* non-paged FLASHS */
rom_4000 = Read_Only 0x4000 to 0x7FFF;
rom_c000 = Read_Only 0xc000 to 0xFEFF;
PLACEMENT
Non_banked, into rom_c000/*, rom_4000*/;

It is very intuitive to see that the two can be directly using the logical address of the page set to non_banked, then the interrupt function in the non_banked, you can put the function in the 64K addressing program segment. In this way, the interruption is more convenient, and the efficiency is much higher.

PID Control formula

How does division get decimals in C language?

In addition to starting with the definition of float, the subsequent division of the time to add. 0, otherwise the results of the computer will be automatically rounded ~ ~: 3/2 results and 3.0/2 results are different ~ ~ because there is no definition 3/2 is floating point, so 3/2 automatic rounding, the result equals 1 and 3.0/ 2, because the pre-use floating-point type to indicate that its result is obviously: 1.5, the division operator "/", if it is two integers divide the result is an integer, if you need to preserve a decimal number when you must convert one of the divisor to a floating-point number

High-speed optocoupler up to 10mbit/s

The standardization of PCB circuit should pay attention to the distribution of inductance distribution capacitance, as well as the transmission of analog signals. inductance capacitor lead to be as short as possible to reduce the distribution capacitance and distribution inductance, circuit board should also pay attention to connect the LC circuit with the amplification circuit as short as possible. Through the line to achieve the cross-board of the line, its signal should be amplified signal, in order to improve the system Snr.

Sometimes the single-chip microcomputer m9s12xs128 AD input channel will be disturbed after an unreasonable reset, this should be noted, if necessary, in the proximity of the MCU input to string into the low-pass network.

Power

1,78xx series of chips are required to input voltage than the output voltage higher than 2v~3v, otherwise it will not work properly. 2, LDO low dropout regulator dropout linear regulator (with respect to conventional linear regulators)

DC-DC Direct flow (to) direct current (conversion of different DC power values) can be called DCDC converters, including LDOs, as long as this definition is met. However, the general argument is that the DC variable (to) DC from the switching mode of implementation of the device called DCDC.

Low-dropout (LDO) linear regulators have the advantage of lower cost, low noise, and a small quiescent current. It requires only a few external components, usually requiring only one or two bypass capacitors. The new Ldo linear regulator achieves the following indicators: The output noise 30ΜV,PSRR is 60dB, the quiescent current 6μa (TI's TPS78001 to Iq=0.5ua), the voltage drop is only 100mV (Ti production of known as 0.1mV Ldo). The performance of an LDO linear regulator can be achieved at this level mainly because the regulator is using a P-channel MOSFET, whereas a common linear regulator uses a PNP transistor. The P-channel MOSFET is voltage-driven and does not require current, so it greatly reduces the current consumed by the device itself; On the other hand, in a circuit that uses a PNP transistor, the voltage drop between the input and output is not too low to prevent the PNP transistor from entering saturation and reducing the output capability , and the voltage drop on the P-channel MOSFET is roughly equal to the product of the output current and the on-resistance. The voltage drop on the MOSFET is very low because the on-resistance of the MOSFETs is very small.

If the input voltage and output voltage is very close, it is best to choose the Ldo regulator, can achieve a high efficiency. So, most of the applications that convert lithium-ion battery voltages to 3V output voltages are LDO regulators. Although 10% of the battery's energy is not in use, the Ldo regulator is still able to keep the battery working longer and with less noise.

If the input voltage and output voltage is not very close, it is necessary to consider switching type of DCDC, because from the above principle can be known that the Ldo input current is basically equal to the output current, if the pressure drop is too large, the energy consumption on the Ldo is too high, inefficient.

DC-to converters include boost, buck, liter/buck, and anti-equivalence circuitry. The advantages of a DC-to converter are high efficiency, large current output, and low quiescent current. With the increase in integration, many new-DC converters require only a few external inductors and filter capacitors. However, the output pulsation and switching noise of this kind of power controller are higher and the cost is relatively high.

3, Pressure drop voltage: refers to the voltage regulator to maintain the output voltage in its rating up to 100mV within the required input voltage and output voltage difference between the minimum value.

4, the static current iq:iquiescent abbreviation, refers to the chip itself consumes the current. In applications such as RF, audio, ADC conversion, PSRR (Power ripple rejection ratio) is an important parameter that embodies the Ldo's ability to resist noise and the higher the PSRR value, the lower the Ldo output ripple

5. Band gap: The difference in energy between the lowest point of the guide band and the peak of the valence band. Also known as the energy gap.

Bandgap reference: bandgap voltage reference, often referred to as bandgap. Is the use of a voltage proportional to the temperature and the diode voltage drop, the two temperature coefficients offset each other, to achieve temperature-independent voltage reference.

[Turn] Electronic technology * Note 4 "2013-03"