XC2700 Datasheet, PDF (56/62 Pages) Infineon Technologies AG – 16/32-Bit Single-Chip Microcontroller

XC2700 Derivatives
XC2000 Family / Alpha Line
Detailed Errata Description
USIC_AI.H001 FIFO RAM Parity Error Handling
A false RAM parity error may be signalled by the USIC module, which may optionally
lead to a trap request (if enabled) for the USIC RAM, under the following conditions:
• a receive FIFO buffer is configured for the USIC module, and
• after the last power-up, less data elements than configured in bit field SIZE have
been received in the FIFO buffer, and
• the last data element is read from the receiver buffer output register OUTRL (i.e. the
buffer is empty after this read access).
Once the number of received data elements is greater than or equal to the receive buffer
size configured in bit field SIZE, the effect described above can no longer occur.
To avoid false parity errors, it is recommended to initialize the USIC RAM before using
the receive buffer FIFO. This can be achieved by configuring a 64-entry transmit FIFO
and writing 64 times the value 0x0 to the FIFO input register IN00 to fill the whole FIFO
RAM with 0x0.
USIC_AI.H002 Configuration of USIC Port Pins
Setting up alternate output functions of USIC port pins through Pn.IOCRy registers
before enabling the USIC protocol (CCR.MODE = 0001_B, 0010_B, 0011_B or 0100_B) might
lead to unintended spikes on these port pins. To avoid the unintended spikes, either of
the following two sequences can be used to enable the protocol:
• Sequence 1:
– Write the initial output value to the port pin through Pn_OMR
– Enable the output driver for the general purpose output through Pn_IOCRx
– Enable USIC protocol through CCR.MODE
– Select the USIC alternate output function through Pn_IOCRx
• Sequence 2:
– Enable USIC protocol through CCR.MODE
– Enable the output driver for the USIC alternate output function through Pn_IOCRx
Similarly, after the protocol is established, switching off the USIC channel by reseting
CCR.MODE directly might cause undesired transitions on the output pin. The following
sequence is recommended:
• Write the passive output value to the port pin through Pn_OMR
• Enable the output driver for the general purpose output through Pn_IOCRx
• Disable USIC protocol through CCR.MODE
Errata Sheet
56
V1.7, 2014-10