Q1: May I know if the reset pin base on diagram 1 will be in a high or low state?
Q2: May I know will this transistor circuit work when MCU triggers the BJT pull to GND to reset MCP23s09

NOTE that : Datasheet state that need external biased (not understand)

 

The RESET pin in the frist diagram will be high and because the signal is internally inverted the IC is NOT in reset state.
Externally biased means that you have to take care of the pin and it is not allowed to leave the pin floating.
The second diagram will work. Maybe you can remove the transistor and connect the MCU pin directly to the RESET pin.

 

The RESET pin in the frist diagram will be high and because the signal is internally inverted the IC is NOT in reset state.
Externally biased means that you have to take care of the pin and it is not allowed to leave the pin floating.
The second diagram will work. Maybe you can remove the transistor and connect the MCU pin directly to the RESET pin.

If I directly connect to the MCU means that MCU gives a low signal meaning MCP will be reset
like this diagram?

 

Yes

 

For future reference, the bar over RESET and the bar over CS in the datasheet show these are active LOW signals.

On the chip schematic symbol, active low pins can be indicated by a bar over the label, or like this: /RESET or #RESET.

 

Do you need to reset the device?
It already has a built-in power-on reset.
You can just connect /Reset to the positive supply.

 

Do you need to reset the device?
It already has a built-in power-on reset.
You can just connect /Reset to the positive supply.

OH yes, I can directly connect to VCC thanks for the reminder.

 

Yes

Hi sir I need to put the pull resistor at the gpio pin as the output is open-drain

 

Hi.
It depends what you want to do with the outputs. If you want do drive a load that is connected to VCC (a relay for example) you don't need a pull up.
Whats on the other side from your GPIOs?
There is also MCP23S08 with push-pull GPIOs.

 

Hi.
It depends what you want to do with the outputs. If you want do drive a load that is connected to VCC (a relay for example) you don't need a pull up.
Whats on the other side from your GPIOs?
There is also MCP23S08 with push-pull GPIOs.

if I connect to the uln2003 driver to control the relay I need to connect a pull-up resistor ?

 

Yes you need a pull-up resistor. Because it is a darlington transistor input the pull up should not be too high. A 1kOhm pull up resistor should work depending how much output current you need out of the uln2003.

 

I AM using this relay

https://www.digikey.my/en/products/...2BSOvc6mF9tsb_uCe0SezIyUOotnIjyQaArx0EALw_wcB

 

Should work properly.

 

Should work properly.

Hi sir may I know the MCP io ic is in NPN or PNP configuration? the datasheet did not state that

 

Hi sir may I know the MCP io ic is in NPN or PNP configuration? the datasheet did not state that

It's open drain - so the output device is an N-channel MOSFET.
Hypothetically, "open drain" could mean a P-channel MOSFET with its source connected to V+, but it never does.

 

Hi sir may I know the MCP io ic is in NPN or PNP configuration? the datasheet did not state that

Ian0 is 100% right:

It's open drain - so the output device is an N-channel MOSFET.
Hypothetically, "open drain" could mean a P-channel MOSFET with its source connected to V+, but it never does.

 

It's open drain - so the output device is an N-channel MOSFET.
Hypothetically, "open drain" could mean a P-channel MOSFET with its source connected to V+, but it never does.

thanks, Ian0 and StefanZe