Atmel AT85RFD-07 Bedienungsanleitung PDF herunterladen (Seite 2)

7656A–MP3–04/07

– after executing, P0 SFR= 1111 1110; P0 port= 1111 1110

Now P0.0 is no more programmed as input. The latch content is set to 0 meaning the port is internally driven to

low level like for an output.

Workaround

To avoid any conflict with port inputs, put all application inputs on same port. If this is not possible, avoid using RMW

instructions and rebuild such instruction by software by taking care to set the Port SFR bit to 1 when writing back to

SFR.

2. SIO Interface – Low Baudrate Data Reception Ready Report

RI flag reset time too long after reading data into the reception FIFO. This may report bad data reception and lead to

double read of received characters.

This errata depends on the CPU frequency and the treatment done on the received character, it appears using polling

mode and using low baudrate values.

Workaround

The goal of the workaround is to leave enough time to the RI flag to be reset to forbid a bad reception (RI=1) detection.

Two workaround are proposed:

– Limit the baudrate to high values, e.g. > 50Kbaud with Fosc= 12MHz, X2 mode and 12x oversampling factor.

– Add a delay between two reads of a character.

3. SPI Interface – DFC Usage Limitation

DFC transfers to SPI do not operate properly when DFC is clocked by PLL.

Workaround

Use DFC transfer only with DFC clocked by oscillator.

4. Battery Monitor – Bad Conversion Linearity

Battery monitor reports bad linearity data.

Workaround

Use the VB4:0 value as threshold voltage conversion only, do not use it for full range voltage conversion.

5. ISP – ISP Entry When Blanked Nand Flash

The ISP mode is not automatically started when first powered-up with new blanked Nand Flash. This case specially

appears when in production.

Workaround

Use a key of the keyboard matrix to force ISP entry at power-up.

This is achieved by connecting any column sig-

nal to ISP pin. Then pressing the key connected to this column and to ROW 0 will assert the ISP pin.

Note that this workaround forbids debug mode as ISP pin is also the OCDT pin. Solution is to add a 0 Ω resistor in

order to insulate the OCDT pin from the keypad during debugging.

For an example on how to apply the workaround, refer to the at85rfd-07 schematic.

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