User's Manual l TQMa335xL UM 0101 l © 2019, TQ-Systems GmbH
Page 9
3.2.1.3
Boot configuration
The boot configuration of the TQMa335xL is defined through 16 GPIO pins.
Note: Boot configuration
None of these 16 boot configuration pins are connected on the TQMa335xL,
which means, the TQMa335xL is delivered with no preset boot configuration.
With bits SYSBOOT[15:14] and SYSBOOT[5] some general settings are carried out, independent from the boot device.
The value in the following table printed in bold is used on account of the 24 MHz oscillator assembled on the TQMa335xL.
The bits SYSBOOT[15:14] set the frequency of the oscillator.
Table 4:
Oscillator frequency
SYSBOOT[15:14]
Oscillator frequency / MHz
Remark
00b
19.2
–
01b
24
Default
10b
25
–
11b
26
–
Bit SYSBOOT[5] indicates whether CLKOUT1 is activated.
Table 5:
General boot configuration CLKOUT1
SYSBOOT[5]
CLKOUT1
0
Deactivated
1
Activated
The boot device or the boot sequence is defined with bits SYSBOOT[4:0].
The following table shows the boot sequence defined for the MBa335x.
Table 6:
Boot device selection
SYSBOOT[4:0]
Boot Sequence
1
st
2
nd
3
rd
4
th
10111b
MMC0 / SD
SPI0 / NOR (not available on TQMa335xL)
UART0 / n.a.
USB0 / n.a.
11100b
MMC1 / eMMC
MMC0 / SD
UART0 / n.a.
USB0 / n.a.
11000b
SPI0 / NOR (not available on TQMa335xL)
MMC0 / SD
USB0 / n.a.
UART0 / n.a.
Attention: Malfunction
On the carrier board must be ensured that even in the third and fourth boot sequence
no pins drive against each other!
