Functional Description
26.1.8.4.5 SYSBOOT Pins
Some of the SYSBOOT pins have special meanings when EMAC boot is selected.
Table 26-35. Ethernet PHY Mode Selection
SYSBOOT[7:6]
PHY Mode
00b
MII
01b
RMII
10b
Reserved
11b
RGMII without internal delay
26.1.8.5 UART Boot Procedure
26.1.8.5.1 Device Initialization
•
UART boot uses UART0.
•
UART0 is configured to run at 115200 baud, 8-bits, no parity, 1 stop bit and no flow control.
26.1.8.5.2 Boot Image Download
•
UART boot uses x-modem client protocol to receive the boot image.
•
Utilities like hyperterm, teraterm, minicom can be used on the PC side to download the boot image to
the board
•
With x-modem packet size of 1K throughout is roughly about 4KBytes/Sec.
•
The ROM code will ping the host 10 times in 3s to start x-modem transfer. If host does not respond,
UART boot will timeout.
•
Once the transfer has started, if the host does not send any packet for 3s, UART boot will time out
•
If the delay between two consecutive bytes of the same packet is more than 2ms, the host is
requested to re-transmit the entire packet again
•
Error checking using the CRC-16 support in x-modem. If an error is detected, the host is requested to
re-transmit the packet again.
26.1.8.5.3 Pins Used
The list of device pins that are configured by the ROM in the case of UART boot mode are as follows.
Note: All the pins might not be driven at boot time.
Table 26-36. Pins Used for UART Boot
Signal name
Pin Used in Device
rx
uart0_rxd
tx
uart0_txd
26.1.8.6 USB Boot Procedure
NOTE:
See AM335x ARM Cortex-A8 Microprocessors (MPUs) Silicon Errata (literature number
) for limitations of USB booting.
26.1.8.6.1 Device Initialization
The ROM code supports booting from the USB interface under the following conditions:
•
When the high-speed USB OTG (USBOTGHS) IP is used through USB0 interface.
•
USB operates in full-speed, client mode.
4147
SPRUH73H – October 2011 – Revised April 2013
Initialization
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