Intel® Agilex™ Hard Processor System Technical Reference Manual

ID 683567
Date 2/14/2023
Public

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13.1.1. HPS_COLD_nRESET Pin Function

You can assign HPS_COLD_nRESET to an available SDM I/O pin. This pin serves both as an input to reset the HPS and as an output to the external system to indicate that the HPS is in reset. Do not connect HPS_COLD_nRESET to the external flash. The SDM controls the reset of the external flash separately. You can configure this pin using the Intel® Quartus® Prime Pro Edition, under Device and Pin options > Configuration > Configuration pin option.

After Power-On-Reset and the SDM has loaded the bitstream, the HPS_COLD_nRESET signal becomes an output and asserts (low), and remains asserted, until User Mode is entered. Then, during User Mode, it becomes an input and is de-asserted (high) through an internal weak pullup resistor and allows the external system to drive this pin asserted when cold reset of the HPS is needed. This behavior is applicable for both Active Serial (AS) and Avalon-ST (AVST) configuration schemes.

The following table describes how the HPS_COLD_nRESET pin behaves during various stages of boot and configuration.

  HPS_COLD_nRESET pin behavior
During USER MODE HPS Cold Reset Trigger has occurred Back in USER MODE
During HPS Reset After HPS Reset After HPS BOOT
HPS Cold Reset Trigger Pin (input) HIGH, user triggers LOW21 (input) user controlled (input) user sets HIGH (output) HIGH (input) HIGH

HPS (Mailbox Command or Watchdog Timeout)22

(input) HIGH, Watchdog Timeout or user sends mailbox command (output) LOW (output) LOW (output) HIGH (input) HIGH
nCONFIG (input) HIGH, user triggers nCONFIG (output) LOW

(output) LOW.

(output) HIGH when nCONFIG goes HIGH and nSTATUS goes HIGH

(output) HIGH (input) HIGH
21 For information about the minimum time assertion of the HPS_COLD_nRESET pin, refer to the Intel® Agilex™ F-Series and I-Series Device Data Sheet
22 In the event of an error, pulse nCONFIG low to reconfigure the HPS and the FPGA fabric to recover.