A Complete List of "English Abbreviations" in Hardware Schematics

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A Complete List of "English Abbreviations" in Hardware Schematics [Copy link]

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Common control interface

EN：Enable. Enable the chip to work. When it is needed, open the EN pin, and when it is not needed, close it. Some chips are high enable, some are low enable, you need to read the specification to know.

CS: Chip Select. Chip selection. Usually used to select which chip to receive when sending data. For example, a SPI bus can be mounted with multiple devices, and a DDR bus can also be mounted with multiple DDR memory chips. At this time, CS is needed to control which device the data is sent to.

RST: Reset, restart. Sometimes it is abbreviated as R or the full name RESET. Sometimes it is marked as RST_N, indicating that the Reset signal is pulled low to take effect.

INT: Interrupt. As mentioned in the previous article, interrupt means that someone wakes you up when you are sleeping, or your girlfriend calls you when you are watching a movie.

PD: Power Down. To power off, you don't necessarily have to cut off the external power supply of the chip. If the chip has its own PD pin, just pull the PD pin, which is equivalent to power off. This line is used on the camera, because the general camera has 3 sets of power supply. It is easier to control the three power supplies to directly cut off the power than to directly operate the PD pin. (There is a Power Delivery in the USB Type-C interface, which is also called PD. It is completely different from this, so don't make a mistake.)

CLK: Clock. The clock line is easy to interfere with others and is also easy to be interfered by others. It needs to be protected during layout. For the clock of the digital transmission bus, it is generally marked as xxx_xCLK, such as SPI_CLK, SDIO_CLK, I2S_MCLK (Main Clock), etc. For the system clock, the frequency is often marked. For example, SYS_26M, 32K, etc. It doesn't matter if the number is marked instead of the three words CLK, because only the clock is marked in this way.

CTRL: control. Writing CONTROL is too long, so it is abbreviated to CTRL, or sometimes CMD (Command).

SW: Switch. Signal line switches, key switches, etc. can all use SW.

PWM: PWM, this is very clear.

REF：Reference, such as I_REF, V_REF, etc. Reference current, reference voltage.

FB: Feedback. Feedback. There will be feedback signals on both the boost and buck circuits, and their meaning is similar to Reference. The chip dynamically adjusts the output according to the voltage collected from the outside. If the external voltage is too low, the output will be increased, and if the external voltage is too high, the output will be reduced.

A/D: Analog/Digital, analog and digital. For example, DBB=Digital Baseband, AGNG=Analog Ground.

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

A/Address: Address line. Same usage as data line. Mainly used in transmission interfaces such as DDR where address and data are separated. Other interfaces, such as slow ones like I2C and SPI, and fast ones like MIPI and RJ45, transmit address and data on a set of lines, so there is no address line.

Common direction signs

TX/RX: Transmit, Receive. This concept is most commonly used in serial ports (UART), where one line is responsible for sending and one line is responsible for receiving. It should be noted here that the sending of one device corresponds to the receiving of another device, and TX should be connected to RX. If TX is connected to TX, both are sending, and no data will be received.

To prevent mistakes, you can mark them as: UART1_MRST, UART1_MTSR. Master RX Slave TX means. Master is the master chip, and Slave is the slave device. It is easy to mark TX and RX incorrectly, especially when the schematic diagram has dozens of pages.

P/N: Positive, Negative. Positive and negative. Used for differential signal lines. Now, except for DDR and SDIO, there are few other parallel data transmission interfaces. USB, LAN, MIPI LCD and Camera, SATA, etc., high-speed data buses have almost become serial transmission data.

The serial signal line speed is very high, easily reaching GHz, and the voltage is very low, only a few hundred millivolts, so it is easy to be interfered with. It is necessary to make a differential signal, that is, use two wires to transmit a data, one for positive and one for negative. When transmitted to the other side, the data is subtracted, the interference signal is subtracted, and the data signal is doubled.

For signals like RESET_N, they are only used as a highlight to indicate that this RESET signal is only effective when it is pulled low. Most devices have a low-effective RESET, and occasionally some devices pull RESET high.

L/R: Left, Right. Usually used in audio cables to distinguish left and right. Sometimes, for example, the signal of a speaker is transmitted via differential transmission, which is indicated by SPK_L_N, SPK_L_P.

As shown in the figure below, the audio output of a 2.1-channel smart speaker (speaker connector end). TAS5751 is an audio amplifier, HF is high frequency (2.1 speakers have a dedicated low frequency output). P and N are replaced by and -.

Common equipment abbreviations

BB: Baseband, baseband processor. More than a decade ago, mobile phone chips only had communication functions and did not have such powerful AP (CPU running the system). The main chips in mobile phones were called Baseband chips. Later, when mobile phones became more powerful, many old engineers were still used to calling the main chip BB instead of CPU.

P (GPIO): Many small chips, such as microcontrollers, have highly universal interfaces. Most of them are GPIO ports, which can be used for anything. Therefore, they are not clearly marked on the pins, but directly marked with P1, P2, P1_3. The number of P is the GPIO number. P1_3 is the third GPIO in the first group. (GPIOs in different groups may have different voltage domains)

BAT: Battery. All battery voltages can be called VBAT.

CHG: Charge.

CAM: Camera.

LCD: Display

TP: Touch Panel. (Be careful not to confuse it with Test Point.)

DC: Direct Current. It is usually used as an external DC input interface on the device, rather than referring to the power supply method or supply voltage. For example, VCC_DC_IN means external DC interface power supply.

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