Regarding the pin description for TCA6416A

shashi poddar

Other Parts Discussed in Thread: IO-EXPANDER-EVM, TCA6416A, PCA9518, TCA9545A

May i get the details of the SDA and SCL for P00 to P07, to which they are connected respectively in expanded mode. I am unable to find which one to be connected to which port, as the details could not be tracked down in the user guide and datasheet.

over 9 years ago

0 Brian Berner over 9 years ago

TI__Mastermind 30260 points

I'm sorry, but I do not understand the question.

Can you please try to re-phrase and ask more details?

Are you using the IO-EXPANDER-EVM?

0 shashi poddar over 9 years ago in reply to Brian Berner

Prodigy 110 points

I am using the TCA6416A pin embedded in a development board, through which i need to connect an I2C device. The TCA6416A chip does not mention the pins to which SDA and SCL of an external device should be connected. So, I needed to know which pin from P00-P07 should be connected to SDA and which one to be connected to SCL.

0 Brian Berner over 9 years ago in reply to shashi poddar

TI__Mastermind 30260 points

If you are using the PW package, SCL and SDA are pins 22 and 23, respectively.

If you are using the RTW package, SCL and SDA are pins 19 and 20, respectively.

If you are using the ZQS package, SCL and SDA are pins A5 and A4, respectively.

0 shashi poddar over 9 years ago in reply to Brian Berner

Prodigy 110 points

Dear Brian,

I am not referring to the input ports. The inputs lines are well specified in datasheet as to which one is SDA and SCL. What i need to know is that out of the pins provided for interfacing an external device, which one is to be connected to SDA and SCL respectively? SDA and SCL you mentioned are for connecting the input of an IIC expander.

Thanks!

0 Brian Berner over 9 years ago in reply to shashi poddar

TI__Mastermind 30260 points

Shashi,

I think you may misunderstand the intended application of of the TCA6416A.

What you are describing sounds more like an I²C hub than an I/O expander.

The only I²C hub we offer is the PCA9518.

We also offer I²C switches (or muxes), such as the TCA9545A.

However, an I/O expander is usually meant to add GPIOs when the processor runs out of GPIO pins. It could also be defined as a serial to parallel converter. None of the output pins are specifically meant to go to other I2C devices.

It is theoretically possible to use sets of P-ports as I²C pins using "bit-banging", but it will severely decrease the speed of this secondary I²C bus and would be labor intensive to write code for.

0 shashi poddar over 9 years ago in reply to Brian Berner

Prodigy 110 points

Thank you very much for your detailed reply.

0 shashi poddar over 9 years ago in reply to shashi poddar

Prodigy 110 points

Dear Brian,

I was further wondering to know, how this IO expander can be used to interface an I2C device. If it has SDA and SCL as input, will it also generate SDA and SCL on different pins for communicating between GPIO and I2C?

0 Brian Berner over 9 years ago in reply to shashi poddar

TI__Mastermind 30260 points

Shashi,

No, an I2C I/O expander will not re-produce the I2C signal on any of the P-port pins.

The I2C bus is designed to be able to "tap" off the main I2C bus and connect to many slaves at the same time, as long as the load capacitance does not exceed 400pF

Can you provide a block diagram of your intended application?

0 shashi poddar over 9 years ago in reply to Brian Berner

Prodigy 110 points

The ZC702 (Xilinx Zynq) has some ports as SCL and SDA which are connected as shown in the diagram below.

Interface

Interface forum

Regarding the pin description for TCA6416A