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Zynq-7000 AP SoC Technical Reference Manual www.xilinx.com 197
UG585 (v1.11) September 27, 2016
Chapter 6: Boot and Configuration
6.3.12 BootROM Error Codes
The BootROM can detect an error while processing the BootROM Header or while processing the
FSBL/User code for decryption and authentication. When a boot failure occurs, the BootROM puts
the device into either a secure or non-secure lockdown; an Error Code is normally generated. The
BootROM flowchart with error conditions is shown in Figure 6-5. The error codes are listed in
Table 6-20.
The error code is visible by observing a bit pulse train on the INIT_B pin (secure lockdown) or by
reading the slcr.REBOOT_STATUS [BOOTROM_ERROR_CODE] bit field (non-secure lockdown).
1. INIT_B pin observations:
°
In secure mode INIT_B pulses the 16-bit error code.
°
In non-secure mode INIT_B drives Low, indicating a failure. JTAG is enabled.
2. JTAG access to error code register read:
°
When JTAG is enabled, the DAP controller can be used to read the error code in the
slcr.REBOOT_STATUS [BOOTROM_ERROR_CODE] register field.
The INIT_B pulses are meant to be visually read with an LED on the INIT_B pin. The pulses are
active-High. A long Low pulse on the pin indicates a
1 and a short pulse indicates a 0. The bit order
is LSB to MSB. The pulse train is repeated three times. An example pulse train is shown in Figure 6-10
using a 60 MHz PS_CLK frequency. The timing will scale linearly with the PS_CLK frequency.
Non-secure boot failures result in the BootROM disabling access to the AES unit, clearing the PL, and
enabling JTAG. The slcr.REBOOT_STATUS register can be read to determine the source of the boot
failure.
Error Code Numbers
The error codes listed in Table 6-20 describe the functionality of production devices. For
preproduction devices, the error code numbers and the reporting scheme are described in
AR# 55082. Other error code numbers might be generated by the BootROM, but are unlikely. If an
error code occurs that is not listed in Table 6-20 for production parts or in
AR# 55082 for
preproduction parts, then contact Xilinx.
X-Ref Target - Figure 6-10
Figure 6-10: Error Code INIT_B Bit Waveform Example
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