Specifications

CY7C67200
Document Number: 38-08014 Rev. *J Page 88 of 93
7. Un-Initialized SIExmsg Registers
■ Problem Definition
The SIE1msg and SIE2msg Registers [0x0144 and 0x0148] are not initialized at power up.
■ Parameters Affected
HPI interrupts.
■ Trigger Conditions
Power-up initialization.
■ Scope of Impact
If using the HPI interface in coprocessor mode, random data will be written to the SIE1msg and SIE2msg Registers [0x0144 and
0x0148] at power up. This will cause two improper HPI interrupts (HPI_INTR) to occur, one for each of the two SIExmsg Registers.
■ Workaround
The external processor should clear the SIExmsg Registers [0x0144 and 0x0148] shortly after nRESET is de-asserted and prior
to the expected processing of proper HPI interrupts (generally 10ms after nRESET is de-asserted.)
■ Fix Status
No fix is currently planned for future silicon versions.
8. BIOS USB Peripheral Mode: Descriptor Length
■ Problem Definition
The BIOS will not properly return a descriptor or set of descriptors if the length is a multiple of the control endpoint’s maximum
packet size.
■ Parameters Affected
Control Endpoint maximum packet size.
■ Trigger Conditions
Get Descriptor requests.
■ Scope of Impact
If the descriptor length is a multiple of the maximum packet size, the BIOS will respond with a STALL instead of a zero-length data
packet for the final IN request.
■ Workaround
If the requested descriptor length is a multiple of the maximum packet size, then either the maximum packet size or the descriptor
length needs to change. A descriptor length can be increased by simply adding a padded byte to the end of a descriptor and
increasing the descriptor Length byte by one. Section 9.5 (Descriptor) of the USB2.0 specification allows a descriptor length to be
larger than the value defined in the specification.
■ Fix Status
No fix is currently planned for future silicon versions.