Does SPI need pull up?
For the SPI operation no pull-ups are needed. Unlike the I2C where pull-ups are needed because the drivers have open collector outputs, no pullups are needed on the SPI signal lines since the drivers have push-pull outputs.
What does pull up mean in circuit?
In electronic logic circuits, a pull-up resistor or pull-down resistor is a resistor used to ensure a known state for a signal. A pull-up resistor effectively establishes an additional loop over the critical components, ensuring that the voltage is well-defined even when the switch is open.
What is pull up and pull-down transistor?
A pull-up resistor connects unused input pins (AND and NAND gates) to the dc supply voltage, (Vcc) to keep the given input HIGH. A pull-down resistor connects unused input pins (OR and NOR gates) to ground, (0V) to keep the given input LOW.
Does I2C need pullup resistors?
I2C communication standard is the mostly widely used inter-chip communication standard in today’s electronic systems. Pullup resistors need to be connected from the I2C lines to the supply to enable communication as shown in Figure 1.
Is SPI active low?
SPI interfaces can have only one master and can have one or multiple slaves. This is normally an active low signal and is pulled high to disconnect the slave from the SPI bus. When multiple slaves are used, an individual chip select signal for each slave is required from the master.
Is SPI open drain?
In general, there is no need for pull up resistors in a SPI implementation, because the pins use a push-pull configuration, rather than Open Drain. The output pins are capable of actively creating their own logical high and low states, rather than relying on pull up resistors to generate a default state.
Should I use pull up or pull down?
To control the current flow, we need those pull-down or pull up resistors. A pull-up resistor allow controlled current flow from supply voltage source to the digital input pins, where the pull-down resistors could effectively control current flow from digital pins to the ground.
What does VCC stand for?
Voltage Common Collector
VCC (Voltage Common Collector) is the power supply of a device .
Why does PMOS pass weak zero?
Like the PMOS in the inverter the NMOS has Vdd to pass and charge C Load. The NMOS transistor will be ‘on’ when its gate voltage is greater or equal to the threshold voltage. As before, a 0 is applied to the gate of our PMOS transistor and since Vgs < Vt it will conduct. (Vt is negative for PMOS transistors.)
How many pull up resistors for I2C?
I2C Current Specifications and Bitrates The I2C specification allows a maximum of 3 mA pull-up current on each I2C line. The Aardvark adapter has two internal pull-up resistors on each line: 2.2k ohm and 100k ohm resistors in parallel. The 2.2k ohm resistor can be turned on and off.