bug(power): external charger limited to 500mA instead of higher IINLIM

[cptkoolbeenz]

Description

When connected to an external charger (wall adapter), the BQ24297 only draws 500mA input current instead of the expected higher limit (up to 2A/3A depending on charger type).

Current Behavior

• USB PC port: 500mA — correct (matches USB 2.0 spec with OTG HIGH)
• External charger: 500mA — should be higher based on charger capability

Expected Behavior

The BQ24297 DPDM detection (Table 9-1 in datasheet) should classify:

• USB host (SDP) + OTG HIGH → 500mA
• Charging port (CDP/DCP) → 3A
• Non-standard adapter → 1A/2A depending on D+/D- divider

The charger should be detected as a charging port or non-standard adapter and IINLIM set accordingly.

Investigation Notes

• AutoSetILim() currently sets IINLIM to 2000mA for all vBusStat cases, so the register write should allow higher current
• The BQ24297 resets IINLIM on every new VBUS plug-in event based on DPDM detection result
• Possible causes:
  • DPDM detection may be misclassifying the charger as USB host due to D+/D- line state
  • The PIC32 USB PHY may be interfering with D+/D- lines during DPDM detection
  • Timing: USB device attach (1000ms delay) may occur before or during DPDM, affecting D+/D- state
  • The AutoSetILim write may be happening before DPDM completes, then DPDM overwrites it
• Datasheet reference: datasheets/bq24297.pdf, sections 9.3.1.3.3 through 9.3.1.3.7

Related

• PR fix(power): OTG HIGH for 500mA DPDM, increase USB attach delay #186: Fixed OTG pin HIGH for 500mA USB host detection
• Issue Add battery management interrupt handling for safe I2C communication #173: Battery management interrupt handling