at32ap7002 ATMEL Corporation, at32ap7002 Datasheet - Page 44

• Manufacturer Part Number: at32ap7002
• Description: Avr 32 32-bit Microcontroller
• Manufacturer: ATMEL Corporation

32054DS–AVR32–10/07
24. HMATRIX - Fixed priority arbitration does not work
25. OSC32 is not available for RTC, WDT, TIMERs and USARTs at startup
26. SPI can generate a false RXREADY signal in SLAVE mode
27. EBI address lines 23, 24, and 25 are pulled up when booting up
28. SSC - Additional delay on TD output
Fixed priority arbitration does not work.
Fix/Workaround
Use Round-robin arbitration instead.
Right after startup the osc32 clock to internal modules is not valid. The osc32 clock will be
valid for use approximately 128 osc32 cycles after the the first instruction is executed. This
has consequences if you are planning to use the RTC, WDT, going into sleep mode and
USARTs with SCK and TCs with TIMER_CLOCK0.
Fix/Workaround
Before executing any code the user should enable the RTC with the smallest prescaler and
poll that the RTC is counting before doing anything in your program. Another way to ensure
that the osc32 is valid is to use interrupts with TOP=1.
Example:
//reset the counter register
//enable the RTC with the smallest prescaler
//wait until the value increases
In slave mode the SPI can generate a false rxready signal during enabling of the SPI or dur-
ing the first transfer.
Fix/Workaround
1. Set slave mode, set required CPOL/CPHA
2. Enable SPI
3. Set the polarity CPOL of the line in the opposite value of the required one
4. Set the polarity CPOL to the required one.
5. Read the RXHOLDING register
Transfers can now begin and RXREADY will now behave as expected.
After reset the EBI address lines 23, 24 and 25 are tristated with pullups. Booting from a
flash larger than 8 MB using these lines will fail, as the flash will be accessed with these
address bits set.
Fix/Workaround
Add external pulldown resistors (5 kΩ) on these lines if booting from a flash larger than 8 MB
using these address lines.
A delay from 2 to 3 system clock cycles is added to TD output when:
AVR32_RTC.val = 0x0;
AVR32_RTC.ctrl = 0x1;
while(AVR32_RTC.val == 0);
AT32AP7002
44