212 lines
8.3 KiB
C
212 lines
8.3 KiB
C
/* Megumin LED display firmware
|
|
* Copyright (C) 2018 Sebastian Götte <code@jaseg.net>
|
|
*
|
|
* This program is free software: you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation, either version 3 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#include <stm32f0xx.h>
|
|
#include <stdint.h>
|
|
#include <system_stm32f0xx.h>
|
|
#include <stm32f0xx_ll_utils.h>
|
|
#include <math.h>
|
|
|
|
#include "serial.h"
|
|
#include "adc.h"
|
|
|
|
unsigned int uart_overruns = 0;
|
|
unsigned int frame_overruns = 0;
|
|
unsigned int invalid_frames = 0;
|
|
|
|
static union tx_buf_union tx_buf;
|
|
volatile union rx_buf_union rx_buf;
|
|
volatile uint8_t framebuf_out_of_sync;
|
|
|
|
void tx_char(uint8_t c) {
|
|
while (!(USART1->ISR & USART_ISR_TC));
|
|
USART1->TDR = c;
|
|
}
|
|
|
|
void send_frame_formatted(uint8_t *buf, int len) {
|
|
uint8_t *p=buf, *q=buf, *end=buf+len;
|
|
do {
|
|
while (*q && q!=end)
|
|
q++;
|
|
tx_char(q-p+1);
|
|
while (*p && p!=end)
|
|
tx_char(*p++);
|
|
p++, q++;
|
|
} while (p <= end);
|
|
tx_char('\0');
|
|
}
|
|
|
|
void send_status_reply(void) {
|
|
tx_buf.desc_reply.firmware_version = FIRMWARE_VERSION;
|
|
tx_buf.desc_reply.hardware_version = HARDWARE_VERSION;
|
|
tx_buf.desc_reply.nbits = NBITS;
|
|
tx_buf.desc_reply.channel_spec = CHANNEL_SPEC;
|
|
tx_buf.desc_reply.nchannels = NCHANNELS;
|
|
tx_buf.desc_reply.color_spec = COLOR_SPEC;
|
|
tx_buf.desc_reply.uptime_s = sys_time_seconds;
|
|
tx_buf.desc_reply.vcc_mv = adc_vcc_mv;
|
|
tx_buf.desc_reply.temp_celsius = adc_temp_celsius;
|
|
tx_buf.desc_reply.uart_overruns = uart_overruns;
|
|
tx_buf.desc_reply.frame_overruns = frame_overruns;
|
|
tx_buf.desc_reply.invalid_frames = invalid_frames;
|
|
send_frame_formatted(tx_buf.byte_data, sizeof(tx_buf.desc_reply));
|
|
}
|
|
|
|
/* This is the higher-level protocol handler for the serial protocol. It gets passed the number of data bytes in this
|
|
* frame (which may be zero) and returns a pointer to the buffer where the next frame should be stored.
|
|
*/
|
|
static volatile inline void packet_received(int len) {
|
|
static enum {
|
|
PROT_ADDRESSED = 0,
|
|
PROT_EXPECT_FRAME_SECOND_HALF = 1,
|
|
PROT_IGNORE = 2,
|
|
} protocol_state = PROT_IGNORE;
|
|
/* Use mac frames as delimiters to synchronize this protocol layer */
|
|
if (len == 1 && rx_buf.byte_data[0] == 0x00) { /* Discovery packet */
|
|
if (sys_time < 100 && sys_time_seconds == 0) { /* Only respond during the first 100ms after boot */
|
|
tx_buf.device_type_reply.mac = MAC_ADDR;
|
|
tx_buf.device_type_reply.device_type = DEVICE_TYPE;
|
|
send_frame_formatted(tx_buf.byte_data, sizeof(tx_buf.device_type_reply));
|
|
}
|
|
|
|
} else if (len == 1) { /* Command packet */
|
|
if (protocol_state == PROT_ADDRESSED) {
|
|
switch (rx_buf.byte_data[0]) {
|
|
case 0x01:
|
|
send_status_reply();
|
|
break;
|
|
}
|
|
} else {
|
|
invalid_frames++;
|
|
}
|
|
protocol_state = PROT_IGNORE;
|
|
|
|
} else if (len == 4) { /* Address packet */
|
|
if (rx_buf.mac_data == MAC_ADDR) { /* we are addressed */
|
|
protocol_state = PROT_ADDRESSED; /* start listening for frame buffer data */
|
|
} else { /* we are not addressed */
|
|
protocol_state = PROT_IGNORE; /* ignore packet */
|
|
}
|
|
|
|
} else if (len == sizeof(rx_buf.set_fb_rq)) {
|
|
if (protocol_state == PROT_ADDRESSED) { /* First of two half-framebuffer data frames */
|
|
/* Kick off buffer transfer. This triggers the main loop to copy data out of the receive buffer and paste it
|
|
* properly formatted into the frame buffer. */
|
|
if (framebuf_out_of_sync == 0) {
|
|
framebuf_out_of_sync = 1;
|
|
} else {
|
|
/* FIXME An overrun happend. What should we do? */
|
|
frame_overruns++;
|
|
}
|
|
|
|
/* Go to "hang mode" until next zero-length packet. */
|
|
protocol_state = PROT_IGNORE;
|
|
}
|
|
|
|
} else {
|
|
/* FIXME An invalid packet has been received. What should we do? */
|
|
invalid_frames++;
|
|
protocol_state = PROT_IGNORE; /* go into "hang mode" until next zero-length packet */
|
|
}
|
|
}
|
|
|
|
void USART1_IRQHandler(void) {
|
|
/* Since a large amount of data will be shoved down this UART interface we need a more reliable and more efficient
|
|
* way of framing than just waiting between transmissions.
|
|
*
|
|
* This code uses "Consistent Overhead Byte Stuffing" (COBS). For details, see its Wikipedia page[0] or the proper
|
|
* scientific paper[1] published on it. Roughly, it works like this:
|
|
*
|
|
* * A frame is at most 254 bytes in length.
|
|
* * The null byte 0x00 acts as a frame delimiter. There is no null bytes inside frames.
|
|
* * Every frame starts with an "overhead" byte indicating the number of non-null payload bytes until the next null
|
|
* byte in the payload, **plus one**. This means this byte can never be zero.
|
|
* * Every null byte in the payload is replaced by *its* distance to *its* next null byte as above.
|
|
*
|
|
* This means, at any point the receiver can efficiently be synchronized on the next frame boundary by simply
|
|
* waiting for a null byte. After that, only a simple state machine is necessary to strip the overhead byte and a
|
|
* counter to then count skip intervals.
|
|
*
|
|
* Here is Wikipedia's table of example values:
|
|
*
|
|
* Unencoded data Encoded with COBS
|
|
* 00 01 01 00
|
|
* 00 00 01 01 01 00
|
|
* 11 22 00 33 03 11 22 02 33 00
|
|
* 11 22 33 44 05 11 22 33 44 00
|
|
* 11 00 00 00 02 11 01 01 01 00
|
|
* 01 02 ...FE FF 01 02 ...FE 00
|
|
*
|
|
* [0] https://en.wikipedia.org/wiki/Consistent_Overhead_Byte_Stuffing
|
|
* [1] Cheshire, Stuart; Baker, Mary (1999). "Consistent Overhead Byte Stuffing"
|
|
* IEEE/ACM Transactions on Networking. doi:10.1109/90.769765
|
|
* http://www.stuartcheshire.org/papers/COBSforToN.pdf
|
|
*/
|
|
|
|
/* Index inside the current frame payload */
|
|
static int rxpos = 0;
|
|
/* COBS state machine. This implementation might be a little too complicated, but it works well enough and I find it
|
|
* reasonably easy to understand. */
|
|
static enum {
|
|
COBS_WAIT_SYNC = 0, /* Synchronize with frame */
|
|
COBS_WAIT_START = 1, /* Await overhead byte */
|
|
COBS_RUNNING = 2 /* Process payload */
|
|
} cobs_state = 0;
|
|
/* COBS skip counter. During payload processing this contains the remaining non-null payload bytes */
|
|
static int cobs_count = 0;
|
|
|
|
if (USART1->ISR & USART_ISR_ORE) { /* Overrun handling */
|
|
uart_overruns++;
|
|
/* Reset and re-synchronize. Retry next frame. */
|
|
rxpos = 0;
|
|
cobs_state = COBS_WAIT_SYNC;
|
|
/* Clear interrupt flag */
|
|
USART1->ICR = USART_ICR_ORECF;
|
|
|
|
} else { /* Data received */
|
|
uint8_t data = USART1->RDR; /* This automatically acknowledges the IRQ */
|
|
|
|
if (data == 0x00) { /* End-of-packet */
|
|
if (cobs_state != COBS_WAIT_SYNC) /* Has a packet been received? */
|
|
/* Process higher protocol layers on this packet. */
|
|
packet_received(rxpos);
|
|
|
|
/* Reset for next packet. */
|
|
cobs_state = COBS_WAIT_START;
|
|
rxpos = 0;
|
|
|
|
} else { /* non-null byte */
|
|
if (cobs_state == COBS_WAIT_SYNC) { /* Wait for null byte */
|
|
/* ignore data */
|
|
|
|
} else if (cobs_state == COBS_WAIT_START) { /* Overhead byte */
|
|
cobs_count = data;
|
|
cobs_state = COBS_RUNNING;
|
|
|
|
} else { /* Payload byte */
|
|
if (--cobs_count == 0) { /* Skip byte */
|
|
cobs_count = data;
|
|
data = 0;
|
|
}
|
|
|
|
/* Write processed payload byte to current receive buffer */
|
|
rx_buf.byte_data[rxpos++] = data;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|