Electronic technology • Note 6 (2013-05\06)

Electronic Technology • Note 6 (2013-05\06)

1, mc9sxs128 MCU IO ,thePORTE Port's minimum two bits can only be input, so PORTE The minimum two bits of the data register for the port are read-only , and the PORTJ port is a special case and can only be effectively manipulated for its lowest two-bit and maximum two bits.

When two pits are in use, the interrupt function must be used as a pittf=0x01;// to clear the interrupt flag bit instead of like pittf_ptf0 = 1 Such a notation; Otherwise, two ways . PIT actually only 1 Road at work

Once the PIT interrupt initialization is enabled, there must be an interrupt function in the code, and if not, the compilation will not be an error, but it is scary to have unpredictable consequences for certain operations.

XS128 Default Entry Interrupt Service Yes,the I bit in CCR is automatically set to 1, disable response to other masked interrupts, interrupt if you want to implement nesting, You need to start a total outage again in a low-level interrupt, such as:

Interrupt vectornumber_vpit1 void Pit_motor (void)

{enableinterrupts;} , will CCR interrupt bit can be shielded in I zeroing, so that advanced interrupts can interrupt low-level interrupts, while low-level interrupts cannot interrupt advanced interrupts.

2, Intelligent Vehicle Path Optimization program:

The unit of the bead is ohm, not hunter

The magnetic bead parameters mainly include: initial magnetic flux (U value ) Curie temperature Operating frequency

The inductor is a storage element, and the magnetic bead is the energy conversion (consumption) device. Inductors are used in the power filter circuit, focusing on suppressing conductive interference, magnetic beads are mostly used in signal circuits, mainly for EMI . Magnetic beads are used to absorb UHF signals, such as some RF circuits,plls, oscillation circuits, including UHF memory circuits (Ddr,sdram,rambus and so on) need to be in the power input part of the magnetic beads, and inductance is a storage element, used in LC Oscillation circuit , low frequency filter circuit, etc., its application frequency range is seldom more than 50MHz.

Four methods to solve the problem of ground interference:

(1) connect with magnetic beads;

(2) electrical capacitance connection;

(3) electrical sense Connection;

(4) with 0 Ohm resistor connection.

The equivalent circuit of the magnetic beads is equivalent to the band-stop limiter, which only has a significant inhibitory effect on the noise of a certain frequency point, and it is necessary to pre-estimate the noise frequency in order to select the appropriate model. For situations where the frequency is uncertain or unpredictable, the bead does not fit.

Capacitance-to-pass, resulting in floating.

The 0 Ohm resistor corresponds to a very narrow current path, which effectively limits the loop current and suppresses the noise. Resistance is attenuated in all frequency bands (0 ohms also has impedance ), which is stronger than magnetic beads.

4. #define MAX (b) ((a) > A):(B))

#define MIN (b) ((a) < (c))? A):(B))

#define ABS (x) (((x) >=0)? ( x):(-(x)))

Electronic technology • Note 6 (2013-05\06)