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Make serial communications framed
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Similar to libsfp, but skipping the CRC.
Reference at
https://github.com/BaroboRobotics/libsfp/wiki/Serial-Framing-Protocol
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@Circuitsoft
Circuitsoft committed Oct 11, 2017
1 parent 287c195 commit 51814b7
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Showing 3 changed files with 99 additions and 42 deletions.
40 changes: 30 additions & 10 deletions pyaci/aci_serial/AciUart.py
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Original file line number Diff line number Diff line change
Expand Up @@ -97,16 +97,29 @@ def stop(self):
self.keep_running = False

def get_packet_from_uart(self):
tmp = bytearray([])
tmp = None
byte_is_escape = False
while self.keep_running:
tmp += bytearray(self.serial.read())
tmp_len = len(tmp)
if tmp_len > 0:
pkt_len = tmp[0]
if tmp_len > pkt_len:
data = tmp[:pkt_len+1]
yield data
tmp = tmp[pkt_len+1:]
byte = self.serial.read(1)
if len(byte):
byte = byte[0]
if (byte & 0xf0) == 0x70:
# Framed byte
if byte == 0x71:
tmp = b''
byte_is_escape = False
if byte == 0x72:
byte_is_escape = True
if tmp and byte == 0x73:
yield tmp
tmp = None
else:
if tmp != None:
if byte_is_escape:
tmp += bytearray([byte ^ 0x20])
byte_is_escape = False
else:
tmp += bytearray([byte])

def run(self):
for pkt in self.get_packet_from_uart():
Expand All @@ -133,9 +146,16 @@ def run(self):
logging.debug("exited read event")

def WriteData(self, data):
data = bytearray(data)
with self._write_lock:
if self.keep_running:
self.serial.write(bytearray(data))
self.serial.write(bytearray([0x71]))
for b in data:
if (b & 0xf0) == 0x70:
self.serial.write(bytearray([0x72]))
b = b ^ 0x20
self.serial.write(bytearray([b]))
self.serial.write(bytearray([0x73]))
self.ProcessCommand(data)

def __repr__(self):
Expand Down
2 changes: 1 addition & 1 deletion rbc_mesh/include/serial_handler.h
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Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef _SERIAL_HANDLER_H__
#define _SERIAL_HANDLER_H__

#define SERIAL_DATA_MAX_LEN (36)
#define SERIAL_DATA_MAX_LEN (72)

#include "serial_evt.h"
#include "serial_command.h"
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99 changes: 68 additions & 31 deletions rbc_mesh/src/serial_handler_uart.c
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Original file line number Diff line number Diff line change
Expand Up @@ -86,8 +86,10 @@ static void do_transmit(void* p_context)
{
if (fifo_pop(&m_tx_fifo, &m_tx_buffer) == NRF_SUCCESS)
{
m_tx_len = ((serial_evt_t*) m_tx_buffer.buffer)->length; /* should be serial_evt_t->length+1, but will be decremented after the push below, so we don't bother */
mp_tx_ptr = &m_tx_buffer.buffer[0];
/* should be serial_evt_t->length+1, but will be decremented after the
* push below, so we don't bother */
m_tx_len = *m_tx_buffer.buffer;
mp_tx_ptr = m_tx_buffer.buffer + 1;

NRF_UART0->EVENTS_TXDRDY = 0;
NRF_UART0->TASKS_STARTTX = 1;
Expand Down Expand Up @@ -120,41 +122,61 @@ static void char_rx(uint8_t c)
{
static serial_data_t rx_buf = {0};
static uint8_t* pp = rx_buf.buffer;
static uint8_t in_packet = 0,
byte_is_escape = 0;

*(pp++) = c;

uint32_t len = (uint32_t)(pp - rx_buf.buffer);
if (len >= sizeof(rx_buf) || (len > 1 && len >= rx_buf.buffer[0] + 1)) /* end of command */
if ((c & 0xf0) == 0x70)
{
if (fifo_push(&m_rx_fifo, &rx_buf) != NRF_SUCCESS)
{
/* respond inline, queue was full */
serial_evt_t fail_evt;
fail_evt.length = 3;
fail_evt.opcode = SERIAL_EVT_OPCODE_CMD_RSP;
fail_evt.params.cmd_rsp.command_opcode = ((serial_cmd_t*) rx_buf.buffer)->opcode;
fail_evt.params.cmd_rsp.status = ACI_STATUS_ERROR_BUSY;
serial_handler_event_send(&fail_evt);
}
else
switch(c)
{
case 0x71:
in_packet = 255;
byte_is_escape = 0;
pp = rx_buf.buffer;
break;
case 0x72:
byte_is_escape = 255;
break;
case 0x73:
in_packet = 0;
if (fifo_push(&m_rx_fifo, &rx_buf) != NRF_SUCCESS)
{
/* respond inline, queue was full */
serial_evt_t fail_evt;
fail_evt.length = 3;
fail_evt.opcode = SERIAL_EVT_OPCODE_CMD_RSP;
fail_evt.params.cmd_rsp.command_opcode = ((serial_cmd_t*) rx_buf.buffer)->opcode;
fail_evt.params.cmd_rsp.status = ACI_STATUS_ERROR_BUSY;
serial_handler_event_send(&fail_evt);
}
else
{
#ifdef BOOTLOADER
NVIC_SetPendingIRQ(SWI2_IRQn);
NVIC_SetPendingIRQ(SWI2_IRQn);
#else
async_event_t async_evt;
async_evt.type = EVENT_TYPE_GENERIC;
async_evt.callback.generic.cb = mesh_aci_command_check_cb;
async_evt.callback.generic.p_context = NULL;
event_handler_push(&async_evt);
async_event_t async_evt;
async_evt.type = EVENT_TYPE_GENERIC;
async_evt.callback.generic.cb = mesh_aci_command_check_cb;
async_evt.callback.generic.p_context = NULL;
event_handler_push(&async_evt);
#endif
}

if (fifo_is_full(&m_rx_fifo))
{
m_serial_state = SERIAL_STATE_WAIT_FOR_QUEUE;
NRF_UART0->TASKS_STOPRX = 1;
}
break;
}

if (fifo_is_full(&m_rx_fifo))
{
m_serial_state = SERIAL_STATE_WAIT_FOR_QUEUE;
NRF_UART0->TASKS_STOPRX = 1;
}
pp = rx_buf.buffer;
}
else if (in_packet)
{
if (byte_is_escape)
*(pp++) = c ^ 0x20;
else
*(pp++) = c;
byte_is_escape = 0;
}
}

Expand Down Expand Up @@ -309,7 +331,22 @@ bool serial_handler_event_send(serial_evt_t* evt)

serial_data_t raw_data;
raw_data.status_byte = 0;
memcpy(raw_data.buffer, evt, evt->length + 1);
uint8_t *buf = raw_data.buffer + 1;
uint8_t *src = (uint8_t*)evt;
uint8_t *end = src + evt->length + 1;
*(buf++) = 0x71;
while (src < end)
{
if ((*src & 0xf0) == 0x70)
{
*(buf++) = 0x72;
*(buf++) = *(src++) ^ 0x20;
}
else
*(buf++) = *(src++);
}
*(buf++) = 0x73;
*raw_data.buffer = (buf - raw_data.buffer) - 2;
fifo_push(&m_tx_fifo, &raw_data);

if (m_serial_state == SERIAL_STATE_IDLE)
Expand Down

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