AT32UC3C0512C Datasheet, PDF (98/110 Pages) ATMEL Corporation – High Performance, Low Power 32-bit AVR Microcontroller

10.1.5 SCIF
10.1.6 SPI
AT32UC3C
1 PLLCOUNT value larger than zero can cause PLLEN glitch
Initializing the PLLCOUNT with a value greater than zero creates a glitch on the PLLEN sig-
nal during asynchronous wake up.
Fix/Workaround
The lock-masking mechanism for the PLL should not be used.
The PLLCOUNT field of the PLL Control Register should always be written to zero.
2 PLL lock might not clear after disable
Under certain circumstances, the lock signal from the Phase Locked Loop (PLL) oscillator
may not go back to zero after the PLL oscillator has been disabled. This can cause the prop-
agation of clock signals with the wrong frequency to parts of the system that use the PLL
clock.
Fix/Workaround
PLL must be turned off before entering STOP, DEEPSTOP or STATIC sleep modes. If PLL
has been turned off, a delay of 30us must be observed after the PLL has been enabled
again before the SCIF.PLL0LOCK bit can be used as a valid indication that the PLL is
locked.
3 BOD33 reset locks the device
If BOD33 is enabled as a reset source (SCIF.BOD33.CTRL=0x1) and when VDDIN_33
power supply voltage falls below the BOD33 voltage (SCIF.BOD33.LEVEL), the device is
locked permanently under reset even if the power supply goes back above BOD33 reset
level. In order to unlock the device, an external reset event should be applied on RESET_N.
Fix/Workaround
Use an external BOD on VDDIN_33 or an external reset source.
1 SPI data transfer hangs with CSR0.CSAAT==1 and MR.MODFDIS==0
When CSR0.CSAAT==1 and mode fault detection is enabled (MR.MODFDIS==0), the SPI
module will not start a data transfer.
Fix/Workaround
Disable mode fault detection by writing a one to MR.MODFDIS.
2 Disabling SPI has no effect on the SR.TDRE bit
Disabling SPI has no effect on the SR.TDRE bit whereas the write data command is filtered
when SPI is disabled. Writing to TDR when SPI is disabled will not clear SR.TDRE. If SPI is
disabled during a PDCA transfer, the PDCA will continue to write data to TDR until its buffer
is empty, and this data will be lost.
Fix/Workaround
Disable the PDCA, add two NOPs, and disable the SPI. To continue the transfer, enable the
SPI and PDCA.
3 SPI disable does not work in SLAVE mode
SPI disable does not work in SLAVE mode.
Fix/Workaround
Read the last received data, then perform a software reset by writing a one to the Software
Reset bit in the Control Register (CR.SWRST).
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