DSP Tips Need to Pay Attention to Several Tips

The digital signal processing chip (DSP) has a high-performance CPU (clock performance exceeding 100 MHz) and high-speed advanced peripherals. Through CMOS processing technology, the power consumption of the DSP chip is getting lower and lower. These huge advances have increased the complexity of DSP board design and faced more similar problems than simple digital circuit designs.

The following are some precautions for DSP hardware design, you can refer to colleagues.

Clock circuit selection principle

1. When the system requires multiple clock signals of different frequencies, the programmable clock chip is preferred;

2, when a single clock signal, select the crystal clock circuit;

3. When multiple clock signals of the same frequency are selected, the crystal oscillator is selected;

4, try to use the PLL inside the DSP chip, reduce the off-chip clock frequency and improve the stability of the system;

5, C6000, C5510, C5409A, C5416, C5420, C5421 and C5441 and other DSP chips have no oscillation circuit, can not use crystal clock circuit;

6, VC5401, VC5402, VC5409 and F281x and other DSP clock signal level is 1.8V, it is recommended to use crystal clock circuit

Processing of unused input/output pins

1. Unused input pins should not be left unconnected, but should be pulled up and pulled down to a fixed level.

1) The key control input pins, such as Ready, Hold, etc., should be fixedly connected to the appropriate state, the Ready pin should be fixedly connected to the active state, and the Hold pin should be fixedly connected to the invalid state.

2) No connection (NC) and reserved (RSV) pins, NC pins: These pins are left unconnected unless otherwise specified. RSV pins: should be connected or not according to the data sheet.

3) Non-critical input pins, pull them up or down to a fixed level to reduce power consumption

2, unused output pins can be left unconnected

3, unused I / O pin: If the state is the input pin, it is handled as a non-critical input pin, pull-up or pull-down to a fixed level; if the state is the output pin, then Can be left unconnected

Why is the DSP with large on-chip RAM high efficiency?

At present, the on-chip memory RAM developed by DSP is getting larger and larger. To design an efficient DSP system, you should select a DSP with a large on-chip RAM. On-chip RAM has the following advantages over off-chip memory:

1) The on-chip RAM is faster, which ensures that the DSP has no waiting operation.

2) For the C2000/C3x/C5000 series, some of the on-chip memory can be accessed twice in one instruction cycle, making the instructions more efficient.

3) The on-chip RAM operates stably without external interference and will not interfere with the outside.

4) Multi-bus on the DSP chip, when accessing the on-chip RAM, it will not affect the access of other buses, and the efficiency is high.

How to write Flash outside the DSP?

DSP external Flash writing method:

1. Programming by the programmer: Convert the OUT file to a format acceptable to the programmer through the HEX conversion program, and then write it by the programmer.

2. Written by DSP software: You need to write the program of Flash according to the description of Flash, load the application and the program that writes Flash into RAM separately, and run the writing program.

DSP external memory control method

For general memory with control signals such as RD, WR, and CS, many DSPs (C3x, C5000) have no control signals directly connected to the memory. The general methods are as follows:

1. CS has address lines and PS, DS or STRB decoding generated;

2./RD=/STRB+/R/W; 3./WR=/STRB+R/W.

How to mix 5V/3.3V?

The development of DSP is the same as the development of integrated circuits. The new DSPs are all 3.3V, but there are still many peripheral circuits that are 5V. Therefore, in DSP systems, there are often mixed problems of 5V and 3.3V DSP. In these systems, you should pay attention to:

1) DSP output to 5V circuit (such as D/A), without adding any buffer circuit, can be directly connected.

2) DSP input 5V signal (such as A/D), because the input signal voltage "4V" exceeds the DSP power supply voltage, the DSP external signal has no protection circuit, need to add buffer, such as 74LVC245, etc., convert 5V signal into 3.3V signal.

3) The signal of the JTAG port of the emulator must also be 3.3V, otherwise the DSP may be damaged.

Basic conditions for DSP work:

1) The DSP power supply and ground connection are correct.

2) The DSP clock is correct.

3) The control signal RS and HOLD signal of the DSP are connected to a high level.

4) The C2000 watchdog is turned off.

5) Non-maskable interrupt NMI pull-up high

6) READY pin pull-up high

Nozzle is a key part of the spraying system,Current contact nozzle should have smooth inner wall,the shape,materials and internal details.

Nozzle

Spray Nozzle,Water Nozzle,Hose Nozzle,High Pressure Nozzle

Shaoxing Tianlong Tin Materials Co.,Ltd. , https://www.tianlongspray.com