"English abbreviations" that equipment engineers need to know

When you look at circuit diagram, you will see many abbreviations marked in English. This article provides some classic and common abbreviations for reference and study.

1 common control interface

EN: turn on, turn on.

Enabling chip to work. When you want to use it, turn on EN pin and turn it off when you don't use it. Some chips turn on at a high level, and some at a low level, it depends on component passport.

CS: chip select, chip select.

Chip selection. Usually used to select which chip to accept when sending data. For example, multiple devices can be installed on a single SPI bus, and multiple DDR memory chips can also be installed on a DDR bus. Currently, CS is needed to control which device to send data to. Typically, it is active low, then have / CS express.

RST: reset, restart.

Sometimes it is abbreviated to R or to full name of RESET. It is sometimes labeled RST_N, indicating that reset signal is driven low to take effect.

INT: interrupt, interrupt.

Interruption means, for example, that someone woke you up while you were sleeping, or your girlfriend called while you were watching a movie, a very commonly used function in processor and corresponding "request" function.

PD: Power Down

Turning off power does not have to turn off external power to chip. If chip has its own PD pin, pulling PD pin directly is equivalent to turning off power. This cable will be used on camera, because ordinary camera has 3 power supplies, and it's easier to drive three power supplies to cut off power directly than to drive PD output directly. (The USB Type-C interface has Power Delivery, also called PD, which is completely different from this. Don't misunderstand.)

CLK: Clock, clock.

Clock lines are easy to get in way and interfere with others, so it needs to be well protected during layout. For digital transmission bus clock, this is usually referred to as xxx_xCLK, eg SPI_CLK, SDIO_CLK, I2S_MCLK (master clock), etc. For system clock, frequency is often referred to as . For example, SYS_26M, 32K, etc. It doesn't matter if number is marked instead of word CLK, because only hours will be marked that way.

CTRL: control, control.

The spelling CONTROL is too long, so it's shortened to CTRL or sometimes CMD (Command).

SW: Switch, switch.

The software can be used for signal line switches, key switches, etc.

PWM: pulse width modulation by outputting pulse signals with different coefficientspadding on output signal line to achieve purpose of transferring power/information, for example, to control speed of motor, adding RC The purpose of voltage regulation is often achieved by PWM in DAC circuit and switching controller of regulator.

REF: link, link.

For example, I_REF, V_REF, etc. Current reference and voltage reference are commonly used in voltage regulator, ADC, and DAC circuits.

FB: feedback, feedback.

The rise and fall circuits will have feedback signals, meaning is similar to reference, microcircuit dynamically adjusts output according to voltage level collected from outside. If external voltage is low, output will be increased, and if external voltage is high, output will be reduced.

A/D: analog/digital, analog and digital.

For example, DBB=Digital Baseband, AGNG=Analog Ground.

D/DATA: data.

I2C is called SDA (Serial DATA), SPI is called SPI_DI, SPI_DO (Data In, Data Out), and DDR data lines are called D0, D1, D32, etc.

A/Address: The address bar.

The usage is same as for data string. It is mainly used on transmission interface where address and data are separated, such as DDR. Other interfaces, slow ones like I2C, SPI, and fast ones like MIPI, RJ45, etc., all addresses and data are transferred over a set of lines, so there is no address line.

2 Determining general directions

TX/RX: transmit, receive, send, and receive.

This concept is most often used for serial ports (UARTs), one line is responsible for sending and other for receiving. Special attention should be paid here, transmission of one device corresponds to reception of another device, and TX must be connected to RX. If TX is connected to TX and both are sent, no data will be received.

It can be tagged as: UART1_MRST, UART1_MTSR to avoid errors. The value of Master RX Slave TX. Master is main control chip and Slave is slave device. TX and RX are easy to get wrong, especially if circuit has dozens of pages.

P/N: positive, negative, positive, and negative.

For differential signal lines. Apart from DDR and SDIO, there are few other parallel data transfer interfaces. USB, LAN, MIPI LCD, Camera, SATA, etc., almost all high-speed data buses have become serial data transfer.

The speed of serial signal line is very high and can accidentally increase to GHz, and voltage is very low, only a few hundred millivolts, so it is easy to tamper with. differential signal, i.e. use two data lines and one positive line. When it is transmitted to other side, data is subtracted, interference signal is subtracted, and data signal is doubled.

For such a signala as RESET_N, it only plays role of an allocation, indicating that RESET signal only takes effect when it goes low. Most devices have RESET active low, and sometimes some devices pull RESET high.

L/R: left, right. Commonly used for audio cables to distinguish between left and right.

Sometimes signals such as speakers are sent through differentials labeled SPK_L_N and SPK_L_P.

As shown in figure below, 2.1ch smart speaker audio output (speaker connector end). TAS5751 is an audio power amplifier and HF is high frequency high frequency (2.1 audio has a dedicated low frequency output). R and H are replaced by and -.

3 common equipment abbreviations

BB: baseband, baseband processor.

More than a decade ago, mobile phone chips only performed communication functions and did not have such a powerful access point (the CPU that runs system). The main chip in a mobile phone was called baseband chip. Later, performance of mobile phones became stronger, and many old engineers still called main chip BB instead of CPU.

P (GPIO): Lots of small chips.

For example, single-chip microcomputer, interface is relatively general, most of them are GPIO ports, which can be used for any purpose, it is not clear to mark pins, use P1, P2, P1_3 to mark directly. The P number is number of GPIOs. P1_3 is third GPIO of first group. (GPIOs of different groups may have different voltage domains)

BAT: battery, battery.

All battery voltages can be called VBAT.

CHG: Pay, charge.

CAM: Camera, camera.

LCD Display: Display.

TP: touch panel, touch screen.

(Be careful not to confuse it with Test Point)

DC: direct current, direct current.

Used on equipment, it is generally used as an external DC input interface, regardless of power supply method or supply voltage. For example, value VCC_DC_IN is an external DC interface power supply.