TPS65988EVM: What if multiple VDM's received on both the USB ports?

Niket Shah2

Part Number: TPS65988EVM

Hi,

I have two queries regarding VDM.

1) Consider one use case in which two devices are connected to the PD controller USB port. What happens if both the devices send the VDM at the same time?

2) How to differentiate which device out of two devices sent the VDM?

over 3 years ago

0 Ghouse Mohiuddin23 over 3 years ago

TI__Expert 7900 points

Only DFP device can send VDM cmd message and UFP device can only send VDM Attention message. You can use USB -PD Analyzer to check on message flow.

0 Niket Shah2 over 3 years ago in reply to Ghouse Mohiuddin23

Prodigy 210 points

Okay.

But what happens if both the UFP devices send the VDM Attention message at the same time. what will be the contents of the "Attention VDM message" register? Will it be overwritten by the latest message?

0 Ghouse Mohiuddin23 over 3 years ago in reply to Niket Shah2

TI__Expert 7900 points

VDM messages are port dependent. 1 UFP on one port will not override the VDM message on the other port.

0 Niket Shah2 over 3 years ago in reply to Ghouse Mohiuddin23

Prodigy 210 points

But PD controller has an I2C register 0x60 and 0x61. How to identify that the contents of the register are related to portr1 or port2?

0 Prajith Cheerakkoda over 3 years ago in reply to Niket Shah2

TI__Expert 8680 points

Hi Niket,

On receiving an interrupt on IRQ1, EC needs to read event register 0x14 from both ports (as shown in the picture below) to identify interrupt event ( INT_EVENTx.VDMReceived) and the interrupt source (Port-0/Port-1). After identifying the port, read the register with the port's I2C address.