Architecture
975
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Host Port Interface (HPI)
21.2.7 Reset Considerations
The HPI has two reset sources: software reset and hardware reset.
21.2.7.1 Software Reset Considerations
The HPI is not affected by a software reset issued by the emulator.
21.2.7.2 Hardware Reset Considerations
When the entire processor is reset with the RESET pin:
•
If the internal strobe signal, internal HSTRB, is high (host is inactive), UHPI_HRDY is driven low and
remains low until the reset condition is over.
•
If internal HSTRB is low (host cycle is active), UHPI_HRDY is driven high, allowing the host to
complete the cycle. When internal HSTRB goes high (cycle is complete), UHPI_HRDY is driven low
and remains low until the reset condition is over. If the active cycle was a write cycle, the memory or
register may not have been correctly updated. If the active cycle was a read cycle, the fetched value
may not be valid.
•
The HPI registers are reset to their default values (see
•
The read and write FIFOs and the associated FIFO logic are reset (this includes a flush of the FIFOs).
•
Host-to-CPU and CPU-to-host interrupts are cleared.
21.2.8 Initialization
The following steps are required to configure the HPI after a hardware reset:
1. Perform the necessary device pin multiplexing setup (see your device-specific data manual).
2. Configure the HPIENA and HPIBYTEAD bits in the chip configuration 1 register (CFGCHIP1) in the
System Configuration (SYSCFG) Module
chapter.
3. Choose how HPIAR and HPIAW will be controlled by configuring the DUALHPIA bit in HPIC.
4. Choose how halfword ordering will be handled by configuring the HWOB bit in HPIC.
5. Choose how the HPI will respond to emulation suspend events by configuring the FREE and SOFT
bits in PWREMU_MGMT.
6. Choose the desired initial addresses and write the addresses to HPIAW and HPIAR, appropriately.
7. Release the HPI logic from reset by clearing the HPIRST bit in HPIC.
The HPI is now ready to perform data transactions.