CryptoAuthLib
Microchip CryptoAuthentication Library
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Hardware Interface Functions - SWI bit-banged. More...
Go to the source code of this file.
Data Structures | |
struct | SWIBuses |
Macros | |
#define | MAX_SWI_BUSES 36 |
SAMD21 xplainned pro has 36 free GPIO pins available. More... | |
Macros for Bit-Banged SWI Timing | |
Times to drive bits at 230.4 kbps. | |
#define | BIT_DELAY_1L delay_us(3) |
#define | BIT_DELAY_1H delay_us(3) |
should be 4.34 us, is 4.05us More... | |
#define | BIT_DELAY_5 delay_us(26) |
#define | BIT_DELAY_7 delay_us(34) |
#define | RX_TX_DELAY delay_us(65) |
#define | START_PULSE_TIME_OUT (600) |
#define | ZERO_PULSE_TIME_OUT (40) |
Functions | |
void | swi_set_pin (uint8_t id) |
Set SWI signal pin. Other functions will use this pin. More... | |
void | swi_enable (void) |
Configure GPIO pin for SWI signal as output. More... | |
void | swi_disable (void) |
Configure GPIO pin for SWI signal as input. More... | |
void | swi_set_signal_pin (uint8_t is_high) |
Set signal pin Low or High. More... | |
void | swi_send_wake_token (void) |
Send a Wake Token. More... | |
void | swi_send_bytes (uint8_t count, uint8_t *buffer) |
Send a number of bytes.This function should not be called directly ,instead should use hal_swi_send() which call this function. More... | |
void | swi_send_byte (uint8_t byte) |
Send one byte. More... | |
ATCA_STATUS | swi_receive_bytes (uint8_t count, uint8_t *buffer) |
Receive a number of bytes.This function should not be called directly ,instead should use hal_swi_receive() which call this function. More... | |
Variables | |
SWIBuses | swi_buses_default |
Hardware Interface Functions - SWI bit-banged.
#define BIT_DELAY_1H delay_us(3) |
should be 4.34 us, is 4.05us
#define BIT_DELAY_1L delay_us(3) |
delay macro for width of one pulse (start pulse or zero pulse) should be 4.34 us, is 4.05 us
#define BIT_DELAY_5 delay_us(26) |
time to keep pin high for five pulses plus stop bit (used to bit-bang CryptoAuth 'zero' bit) should be 26.04 us, is 26.92 us
#define BIT_DELAY_7 delay_us(34) |
time to keep pin high for seven bits plus stop bit (used to bit-bang CryptoAuth 'one' bit) should be 34.72 us, is 35.13 us
#define MAX_SWI_BUSES 36 |
SAMD21 xplainned pro has 36 free GPIO pins available.
#define RX_TX_DELAY delay_us(65) |
turn around time when switching from receive to transmit should be 93 us (Setting little less value as there would be other process before these steps)
#define START_PULSE_TIME_OUT (600) |
Lets set the timeout value for start pulse detection to the uint8_t maximum. This value is decremented while waiting for the falling edge of a start pulse.
#define ZERO_PULSE_TIME_OUT (40) |
Maximum time between rising edge of start pulse and falling edge of zero pulse is 8.6 us. Therefore, a value of 40 (around 15 us) gives ample time to detect a zero pulse and also leaves enough time to detect the following start pulse. This value is decremented while waiting for the falling edge of a zero pulse.
void swi_disable | ( | void | ) |
Configure GPIO pin for SWI signal as input.
void swi_enable | ( | void | ) |
Configure GPIO pin for SWI signal as output.
ATCA_STATUS swi_receive_bytes | ( | uint8_t | count, |
uint8_t * | buffer | ||
) |
Receive a number of bytes.This function should not be called directly ,instead should use hal_swi_receive() which call this function.
[in] | count | number of bytes to receive |
[out] | buffer | pointer to receive buffer |
Receive bits and store in buffer.
Detect start bit.
Wait for falling edge.
Wait for rising edge.
let's just wait the maximum time for the falling edge of a zero bit to arrive after we have detected the rising edge of the start bit.
Detect possible edge indicating zero bit.
Wait for rising edge of zero pulse before returning. Otherwise we might interpret its rising edge as the next start pulse.
Update byte at current buffer index.
received "one" bit
Indicate that we timed out after having received at least one byte.
void swi_send_byte | ( | uint8_t | byte | ) |
Send one byte.
[in] | byte | byte to send |
void swi_send_bytes | ( | uint8_t | count, |
uint8_t * | buffer | ||
) |
Send a number of bytes.This function should not be called directly ,instead should use hal_swi_send() which call this function.
[in] | count | number of bytes to send. |
[in] | buffer | pointer to buffer containing bytes to send |
< Send Logic 1 (7F)
< Send Logic 0 (7D)
void swi_send_wake_token | ( | void | ) |
Send a Wake Token.
void swi_set_pin | ( | uint8_t | id | ) |
Set SWI signal pin. Other functions will use this pin.
[in] | id | definition of GPIO pin to be used |
void swi_set_signal_pin | ( | uint8_t | is_high | ) |
Set signal pin Low or High.
[in] | is_high | 0: Low, else: High. |
SWIBuses swi_buses_default |