Brief overview of our system (Kind of Charge through Dongle application):
- Our Cypress controlled Hub uses CYPD3125 & CYUSB 3304 & is DRP capable
- When AC power is available: Hub will be a Source & charges tablet
- When AC power is Not available: Tablet sources power. Hub + Devices sinks tabler power
Refer to attached image Overview.png
While most of the Samsung S3 tablets with dead battery tablet are chargeable some are not chargeable. Which means we never see a voltage (Vsafe) on VBus.
Please find the attached logs (Use Teledyne Lecroy's USB Protocol Suite tool to open the CC logs).
a. Good tablet.usb: This is a log for good tablet whose battery is dead & is chargeable.
b. Bad tablet.usb: This is a log for bad tablet whose battery is dead & is NOT chargeable.
c. Bad tablet with a modified Initialization seq as below:
dpm_update_port_config(0, PRT_ROLE_SOURCE, PRT_ROLE_SOURCE, false, TRY_SRC_TRY_SNK_DISABLED);
dpm_update_port_config(0, PRT_ROLE_SOURCE, PRT_ROLE_SOURCE, false, TRY_SRC_ENABLED);
Note: We initialize the Hub as a 'PRT_ROLE_SOURCE' or 'PRT_ROLE_SINK' based on the AC power availability, instead of a 'PRT_DUAL'.
Bad tablet with modified Initialization seq.usb: This is log for this configuration.
Always configured it to SRC here, so that the Hub always presents Rp, while we see that the Tablet is always presenting Rd. The negotiation still isn't initiated.
No PD logs for the bad tablets.
Let me know if you want more information. Awaiting for your response.
Thanks & Regards