UART1 Mode 1 with Timer2 1T

Macros
#define	uart1_mode1_timer2_1T_init(pins)
	Initialize UART1 in Mode 1 with Timer2 1T configuration.
#define	uart1_mode1_timer2_1T_start(baudrate)
	Start UART1 communication with standart baudrate value.
#define	uart1_mode1_timer2_1T_ticks(baudrate)   (65536 - (((MAIN_Fosc / baudrate) >> 2) >> get_frequency_divider_scale()))
	Get UART1 ticks for given baudrate and frequency divider scale.
#define	uart1_mode1_timer2_1T_start_ext(baudrate)
	Start UART1 communication with baudrate value.
#define	uart1_mode1_timer2_1T_stop   (bit_clr(AUXR, CBIT4))
	Stop UART1 communication and disable Timer2.
#define	is_uart1_mode1_timer2_1T_started()   (test_if_bit_set(AUXR, SBIT4))
	Is UART1 started?

Enumerations
enum	uart1_mode1_timer2_1t_baudrate_t {   baudrate_1200 = 0xF6FF , baudrate_2400 = 0xFB80 , baudrate_4800 = 0xFDC0 , baudrate_9600 = 0xFEE0 ,   baudrate_19200 = 0xFF70 , baudrate_38400 = 0xFFB8 , baudrate_57600 = 0xFFD0 , baudrate_115200 = 0xFFE8 }
	UART1 precalculated baudrates. More...

Detailed Description

Functions and data structures for UART1 communication in Mode 1 with Timer2 1T as baudrate generator. Dont use Timer2 for other purposes.

This module implements UART1 point-to-point communication. Relay and broadcast features are not supported by this module.

UART1 Mode 1 provides 8-bit asynchronous communication with variable baud rate. Sent data is transmitted to the TxD pin, and received data is read from the RxD pin. The frame data includes one start bit, 8 data bits, and one stop bit. 8-N-1

UART1 baudrate is determined by the T2 overflow rate. T2 overflow rate is configured by setting T2H and T2L registers.

THTL = 65536 - Sysclk/(4 * baudrate). Sysclk = master clock frequency / frequency divder.

THTL value is precalulated for standard baudrates with none freq divider.

In UART1 Mode 1, three sets of RxD/TxD pins can be used: RxD on P3.0/TxD on P3.1, RxD on P3.6/TxD on P3.7 and RxD on P1.6/TxD on P1.7.

Typical usage:

uart1_mode1_timer2_1T_init(RxD_P30_TxD_P31);
uart1_mode1_timer2_1T_start(baudrate_9600);
 
for (;;)
{
 // Send or receive data
}

See also

uart1_send_byte()

uart1_receive_byte()

is_uart1_send_byte_complete()

is_uart1_receive_byte_complete()

Author

Michael Golovanov

Macro Definition Documentation

is_uart1_mode1_timer2_1T_started

#define is_uart1_mode1_timer2_1T_started

(

)

(test_if_bit_set(AUXR, SBIT4))

Is UART1 started?

Returns

bool returns true if UART1 started otherwise false.

uart1_mode1_timer2_1T_init

#define uart1_mode1_timer2_1T_init

(

pins

)

Value:

do {                                        \
                                            \
    enable_mcu_interrupts();                \
    enable_uart1_interrupt();               \
    disable_timer2_interrupt();             \
                                            \
    PCON &= 0x3F;                           \
    SCON = 0x50;                            \
                                            \
    /* The clock source of Timer 2 is SYSclk/12. AUXR.T2x12 = 0 */  \
    /* AUXR.UART_M0x6 = 0 */                                        \
    /* Timer2 is not started. AUXR.T2R = 0 */                       \
    /* Timer2 are used as timer. AUXR.T2_C/T = 0 */                 \
    AUXR &= 0xC2;                           \
                                            \
    /* Select Timer2 as UART1 baud rate generator. AUXR.S1ST2 = 1; */ \
    bit_set(AUXR, SBIT0);                   \
    /* The clock source of Timer 2 is SYSclk. AUXR.T2x12 = 1 */       \
    bit_set(AUXR, SBIT2);                   \
                                            \
    /* Point-to-point mode */               \
    bit_clr(CLK_DIV, CBIT4);                \
                                            \
    /* Set AUXR1 bits 6, 7 to select RxD/TxD pins */                 \
    AUXR1 &= 0x3F;                          \
    AUXR1 |= pins;                          \
} while(0)

Initialize UART1 in Mode 1 with Timer2 1T configuration.

The clock source of Timer2 is SYSclk. AUXR.T2x12 = 1. AUXR.UART_M0x6 = 0. Timer2 are used as timer. AUXR.T2_C/T = 0. Timer2 is not started. AUXR.T2R = 0.

See also

uart1_pins_t

Parameters

pins	Pin configuration from uart1_pins_t enum

Note

Must be called before starting UART communication

uart1_mode1_timer2_1T_start

#define uart1_mode1_timer2_1T_start

(

baudrate

)

Value:

do {                                                    \
    /* Set TH TL values */                              \
    T2L = baudrate & 0xFF;                              \
    T2H = baudrate >> 8;                                \
                                                        \
    /* Start Timer2 */                                  \
    bit_set(AUXR, SBIT4);                               \
} while(0)

Start UART1 communication with standart baudrate value.

Parameters

baudrate

const uart1_mode1_timer2_1t_baudrate_t Baudrate selection from uart1_mode1_timer2_1t_baudrate_t enum

Note

Before calling this function, uart1_mode1_timer2_1T_init() must be called.

Enum contains standard baudrates with precalculated THTL values for 1T mode

Warning

UART1 mode1 in this routine is biased by frequency divider.

uart1_mode1_timer2_1T_start_ext

#define uart1_mode1_timer2_1T_start_ext

(

baudrate

)

Value:

do {                                                            \
    const uint16_t ticks = uart1_mode1_timer2_1T_ticks(baudrate);\
                                                                \
    /* Set TH TL values */                                      \
    T2L = ticks & 0xFF;                                         \
    T2H = ticks >> 8;                                           \
                                                                \
    /* Start Timer2 */                                          \
    bit_set(AUXR, SBIT4);                                       \
} while (0)

Start UART1 communication with baudrate value.

Parameters

baudrate

const uint32_t Baudrate value. Value may be non standard (not in 1200, 9600 etc).

Note

Before calling this function, uart1_mode1_timer2_1T_init() must be called.

Attention

This function is not baudrate overflow safe.

uart1_mode1_timer2_1T_stop

#define uart1_mode1_timer2_1T_stop   (bit_clr(AUXR, CBIT4))

Stop UART1 communication and disable Timer2.

Warning

Calling this function will terminate any ongoing communication

uart1_mode1_timer2_1T_ticks

#define uart1_mode1_timer2_1T_ticks

(

baudrate

)

(65536 - (((MAIN_Fosc / baudrate) >> 2) >> get_frequency_divider_scale()))

Get UART1 ticks for given baudrate and frequency divider scale.

Ticks used as input parameter for uart1_mode1_timer2_1T_start_ext()

Parameters

baudrate

uint32_t baudrate

Returns

uint16_t baudrate ticks

Attention

This function is not overflow safe. The value of (((MAIN_Fosc / baudrate) >> 2) >> get_frequency_divider_scale()) should be less than 65535 (uint16_t).

Enumeration Type Documentation

uart1_mode1_timer2_1t_baudrate_t

enum uart1_mode1_timer2_1t_baudrate_t

UART1 precalculated baudrates.

Enumerator
baudrate_1200	1200 baudrate
baudrate_2400	2400 baudrate
baudrate_4800	4800 baudrate
baudrate_9600	9600 baudrate
baudrate_19200	19200 baudrate
baudrate_38400	38400 baudrate
baudrate_57600	57600 baudrate
baudrate_115200	115200 baudrate