Posted on January 26, 2017 at 11:20#define sbi(port,bit) port |= (1<<bit)
#define cbi(port,bit) port &= ~(1<<bit)
#define cb(port,bit) port & (1<<bit)
void
clock_setup
(
)
;
void
spi_master_setup
(
)
;
void
spi_tx
(
unsigned
char
tx
)
;
void
gpio_init
(
)
;
void
spi_enable
(
)
;
void
clock_setup
(
)
{
sbi
(
RCC
->
APB2ENR
,
12
)
;
//enable clock for SPI1
sbi
(
RCC
->
AHB1ENR
,
0
)
;
//enable clock for GPIOA
}
void
spi_master_setup
(
)
{
cbi
(
SPI1
->
CR1
,
15
)
;
//spi 2 line unidirection full duplex
sbi
(
SPI1
->
CR1
,
2
)
;
//spi1 in master mode
cbi
(
SPI1
->
CR1
,
11
)
;
//SPI1 in 8 bit data format
sbi
(
SPI1
->
CR1
,
1
)
;
//CPOL=1 clock polarity 1 when idle
sbi
(
SPI1
->
CR1
,
0
)
;
//CPHA=1 second clock transition is the first data capture edge
cbi
(
SPI1
->
CR1
,
9
)
;
//NSS software slave management---------------
SPI1
->
CR1
&=
~
(
(
1
<<
3
)
|
(
1
<<
4
)
|
(
1
<<
5
)
)
;
//000 for prescaler fpclk/2
cbi
(
SPI1
->
CR1
,
7
)
;
//MSB first
}
void
gpio_init
(
)
{
GPIOA
->
MODER
|=
(
(
1
<<
11
)
|
(
1
<<
13
)
|
(
1
<<
15
)
)
;
//set A5,A6,A7 as alternate function mode
GPIOA
->
OTYPER
&=
~
(
(
1
<<
5
)
|
(
1
<<
6
)
|
(
1
<<
7
)
)
;
//output type pushpull
GPIOA
->
OSPEEDR
&=
~
(
(
1
<<
10
)
|
(
1
<<
11
)
|
(
1
<<
12
)
|
(
1
<<
13
)
|
(
1
<<
14
)
|
(
1
<<
15
)
)
;
//output speed
GPIOA
->
AFR
[
0
]
|=
(
(
1
<<
20
)
|
(
1
<<
22
)
)
;
//select AF5 for SPI_SCK
GPIOA
->
AFR
[
0
]
|=
(
(
1
<<
24
)
|
(
1
<<
26
)
)
;
//select AF5 for SPI_MISO
GPIOA
->
AFR
[
0
]
|=
(
(
1
<<
28
)
|
(
1
<<
30
)
)
;
//select AF5 for SPI_MISO
sbi
(
GPIOA
->
MODER
,
0
)
;
//set 0th bit to set GPIOA_0 as output mode
cbi
(
GPIOA
->
OTYPER
,
0
)
;
//Push-pull
GPIOA
->
OSPEEDR
&=
~
(
(
1
<<
0
)
|
(
1
<<
1
)
)
;
//low speed
sbi
(
GPIOA
->
ODR
,
0
)
;
}
void
spi_enable
(
)
{
sbi
(
SPI1
->
CR1
,
6
)
;
}
void
spi_tx
(
unsigned
char
tx
)
{
cbi
(
GPIOA
->
ODR
,
0
)
;
tx
=
SPI1
->
DR
;
while
(
!
(
cb
(
SPI1
->
SR
,
1
)
)
)
;
SPI1
->
DR
=
tx
;
sbi
(
GPIOA
->
ODR
,
0
)
;
}
void
delayf
(
unsigned
int
x
)
;
int
main
(
)
{
unsigned
char
tx
=
0
;
clock_setup
(
)
;
spi_master_setup
(
)
;
gpio_init
(
)
;
spi_enable
(
)
;
while
(
1
)
{
tx
++;
spi_tx
(
tx
)
;
delayf
(
10
)
;
}
}
void
delayf
(
unsigned
int
x
)
{
unsigned
int
i
,
j
;
for
(
i
=
0
;
i
<
x
;
i
++
)
{
for
(
j
=
0
;
j
<
1000
;
j
++
)
;
}
}
above code is for spi interfacing with stm32f407vg discovery board...i wrote my own bare-metal code...and i just debug this code with st-link debugger provided on board with keilV5 IDE...here my code is for spi master mode..and when i enable spi SPE(spi enable bit) it will automatically reset MSTR(Master mode bit) bit..and it behaves like slave mode and i debug this code many times but i couldn't identify where i am doing wrong..
please help us little bit...
