the default configuration of the UART is 8N1: 8 data bits, no parity , one stop bit.
I need to change this settings, i.e. 7E2.
In "driver/uart.h" there are some definitions to do that:
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typedef enum {
FIVE_BITS = 0x0,
SIX_BITS = 0x1,
SEVEN_BITS = 0x2,
EIGHT_BITS = 0x3
} UartBitsNum4Char;
typedef enum {
ONE_STOP_BIT = 0,
ONE_HALF_STOP_BIT = BIT2, //0x00000004
TWO_STOP_BIT = BIT2
} UartStopBitsNum;
typedef enum {
NONE_BITS = 0,
ODD_BITS = 0,
EVEN_BITS = BIT4 //0x00000010
} UartParityMode;
typedef enum {
STICK_PARITY_DIS = 0,
STICK_PARITY_EN = BIT3 | BIT5 // 0x00000008| 0x00000020
} UartExistParity;
In uart_config(uint8 uart_no), defined in "driver/uart.c", this enum are used to set the UART register.
Here I added the typecasts to show the enum typedefs.
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WRITE_PERI_REG(UART_CONF0(uart_no), (UartExistParity) UartDev.exist_parity
| (UartParityMode) UartDev.parity
| ((UartStopBitsNum)UartDev.stop_bits << UART_STOP_BIT_NUM_S)
| ((UartBitsNum4Char)UartDev.data_bits << UART_BIT_NUM_S));
with
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#define UART_CONF0( i ) (REG_UART_BASE( i ) + 0x20)
#define REG_UART_BASE( i ) (0x60000000+(i)*0xf00)
#define UART_STOP_BIT_NUM_S 4
#define UART_BIT_NUM_S 2
this definition conflict at bit 3:
UartDev.data_bits << 2 => the bits of UartBitsNum4Char are now in bit 2+3
UartDev.exist_parity => STICK_PARITY_EN = BIT3 | BIT5
I found in this forum Uart_reg_release_141118.xls with the register definition:
UART_CONF0 UART_CONF0
...
stop_bit_num [5:4] 2'd1 R/W Set stop bit: 1:1bit 2:1.5bits 3:2bits
bit_num [3:2] 2'd3 R/W Set bit num: 0:5bits 1:6bits 2:7bits 3:8bits
parity_en [1] 1'b0 R/W Set this bit to enable uart parity check
parity [0] 1'b0 R/W Set parity check: 0:even 1:odd
If this definition are correct, so the above typedefs in "driver/uart.h" must be:
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typedef enum {
STICK_PARITY_DIS = 0, // No parity
STICK_PARITY_EN = BIT1
} UartExistParity;
typedef enum {
ODD_BITS = BIT0,
EVEN_BITS = 0
} UartParityMode;
typedef enum {
ONE_STOP_BIT = 1,
ONE_HALF_STOP_BIT = 2,
TWO_STOP_BIT = 3
} UartStopBitsNum;
Then the function call in uart_config(uint8 uart_no)
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WRITE_PERI_REG(UART_CONF0(uart_no), UartDev.exist_parity
| UartDev.parity
| (UartDev.stop_bits << UART_STOP_BIT_NUM_S)
| (UartDev.data_bits << UART_BIT_NUM_S));correspond with Uart_reg_release_141118.xls
uart.c contain
// UartDev is defined and initialized in rom code.
extern UartDevice UartDev;
The initialized value from rom code of (UartStopBitsNum) UartDev.stop_bits is 0.
But this value is not in the register documentation:
stop_bit_num [5:4] 2'd1 R/W Set stop bit: 1:1bit 2:1.5bits 3:2bits
So it should set to ONE_STOP_BIT = 1.
What happen if the register bits stop_bit_num are set to 0?
Peter