Difference between revisions of "AVR serial communications"
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(Created page with 'Notes on getting serial communications to work on AVR. ==Registers== ;UCSRB: (USART Control and Status Register B) In this register, set RXEN to enable serial reception and TXEN …') |
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Notes on getting serial communications to work on AVR. | Notes on getting serial communications to work on AVR. | ||
==Registers== | ==Registers== | ||
| − | ;UCSRB | + | ;Enabling USART functions: Set RXEN and TXEN in '''UCSRB''' (USART Control and Status Register B) to enable serial reception. |
| − | ;UBRR | + | ;Setting the baudrate: '''UBRR''' (USART Baud Rate Register) Sets the baud rate. The baud rate is f<sub>osc</sub>/(UBBR+1) '''divided''' by 2, 8 (U2X = 1) or 16 (U2X = 0). U2X is located in '''UCSRA'''. |
| + | ;Choosing the frame format: UCSZ0 - UCSZ1 (in '''UCSRC'''), and UCSZ2 (in '''UCSRB''') can be used to set the number of databits (USART Character Size: 5, 6, 7, 8, ''reserved'', ''reserved'', ''reserved'',9) . UPM0 - UPM1 (USART Parity mode: none, ''reserved'', even, odd) and USBS (USART Stop Bit Select: one bit, two bit) are in '''UCSRC'''. Default is ''8n1''. '''Note''': on atmega16, al writes to UCSRC must have bit ''URSEL'' set, otherwise the write will redirect to the UBRRH register. | ||
Revision as of 00:39, 3 December 2009
Notes on getting serial communications to work on AVR.
Registers
- Enabling USART functions
- Set RXEN and TXEN in UCSRB (USART Control and Status Register B) to enable serial reception.
- Setting the baudrate
- UBRR (USART Baud Rate Register) Sets the baud rate. The baud rate is fosc/(UBBR+1) divided by 2, 8 (U2X = 1) or 16 (U2X = 0). U2X is located in UCSRA.
- Choosing the frame format
- UCSZ0 - UCSZ1 (in UCSRC), and UCSZ2 (in UCSRB) can be used to set the number of databits (USART Character Size: 5, 6, 7, 8, reserved, reserved, reserved,9) . UPM0 - UPM1 (USART Parity mode: none, reserved, even, odd) and USBS (USART Stop Bit Select: one bit, two bit) are in UCSRC. Default is 8n1. Note: on atmega16, al writes to UCSRC must have bit URSEL set, otherwise the write will redirect to the UBRRH register.