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canbus: Rework CAN command protocol 

Rework the micro-controller command protocol so that it supports
direct communication with the serialqueue.c code.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
Kevin O'Connor 2021-02-07 15:23:19 -05:00
parent 041692828c
commit 6cb419a90a
5 changed files with 162 additions and 74 deletions
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65
docs/CANBUS_protocol.md Normal file
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@ -0,0 +1,65 @@
This document describes the protocol Klipper uses to communicate over
[CAN bus](https://en.wikipedia.org/wiki/CAN_bus).
# Micro-controller id assignment
Klipper uses only CAN 2.0A standard size CAN bus packets, which are
limited to 8 data bytes and an 11-bit CAN bus identifier. In order to
support efficient communication, each micro-controller is assigned at
run-time a unique 1-byte CAN bus nodeid (`canbus_nodeid`) for general
Klipper command and response traffic. Klipper command messages going
from host to micro-controller use the CAN bus id of `canbus_nodeid *
2 + 256`, while Klipper response messages from micro-controller to
host use `canbus_nodeid * 2 + 256 + 1`.
Each micro-controller has a factory assigned unique chip identifier
that is used during id assignment. This identifier can exceed the
length of one CAN packet, so a hash function is used to generate a
unique 6-byte id (`canbus_uuid`) from the factory id.
# Admin messages
Admin messages are used for id assignment. Admin messages sent from
host to micro-controller use the CAN bus id `0x3f0` and messages sent
from micro-controller to host use the CAN bus id `0x3f1`. All
micro-controllers listen to messages on id `0x3f0`; that id can be
thought of as a "broadcast address".
## CMD_QUERY_UNASSIGNED message
This command queries all micro-controllers that have not yet been
assigned a `canbus_nodeid`. Unassigned micro-controllers will respond
with a RESP_NEED_NODEID response message.
The CMD_QUERY_UNASSIGNED message format is:
`<1-byte message_id = 0x00>`
## CMD_SET_NODEID message
This command assigns a `canbus_nodeid` to the micro-controller with a
given `canbus_uuid`.
The CMD_SET_NODEID message format is:
`<1-byte message_id = 0x01><6-byte canbus_uuid><1-byte canbus_nodeid>`
## RESP_NEED_NODEID message
The RESP_NEED_NODEID message format is:
`<1-byte message_id = 0x20><6-byte canbus_uuid>`
# Data Packets
A micro-controller that has been assigned a nodeid via the
CMD_SET_NODEID command can send and receive data packets.
The packet data in messages using the node's receive CAN bus id
(`canbus_nodeid * 2 + 256`) are simply appended to a buffer, and when
a complete [mcu protocol message](Protocol.md) is found its contents
are parsed and processed. The data is treated as a byte stream - there
is no requirement for the start of a Klipper message block to align
with the start of a CAN bus packet.
Similarly, mcu protocol message responses are sent from
micro-controller to host by copying the message data into one or more
packets with the node's transmit CAN bus id (`canbus_nodeid * 2 +
256 + 1`).

2
docs/Overview.md
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@ -60,6 +60,8 @@ communication with the Klipper developers.
control API.
- [MCU commands](MCU_Commands.md): A description of low-level commands
implemented in the micro-controller software.
- [CAN bus protocol](CANBUS_protocol.md): Klipper CAN bus message
format.
- [Debugging](Debugging.md): Information on how to test and debug
Klipper.
- [Benchmarks](Benchmarks.md): Information on the Klipper benchmark

135
src/generic/canbus.c
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@ -82,80 +82,88 @@ console_sendf(const struct command_encoder *ce, va_list args)
/****************************************************************
* CAN command handling
* CAN "admin" command handling
****************************************************************/
static uint8_t receive_buf[192], receive_pos;
DECL_CONSTANT("RECEIVE_WINDOW", ARRAY_SIZE(receive_buf));
// Available commands and responses
#define CANBUS_CMD_QUERY_UNASSIGNED 0x00
#define CANBUS_CMD_SET_NODEID 0x01
#define CANBUS_RESP_NEED_NODEID 0x20
static void
can_process_data(uint32_t id, uint32_t len, uint8_t *data)
// Helper to verify a UUID in a command matches this chip's UUID
static int
can_check_uuid(uint32_t id, uint32_t len, uint8_t *data)
{
int rpos = receive_pos;
if (len > sizeof(receive_buf) - rpos)
len = sizeof(receive_buf) - rpos;
memcpy(&receive_buf[rpos], data, len);
receive_pos = rpos + len;
return len >= 7 && memcmp(&data[1], canbus_uuid, sizeof(canbus_uuid)) == 0;
}
// Helper to retry sending until successful
static void
canbus_send_blocking(uint32_t id, uint32_t len, uint8_t *data)
// Helpers to encode/decode a CAN identifier to a 1-byte "nodeid"
static int
can_get_nodeid(void)
{
if (!canbus_assigned_id)
return 0;
return (canbus_assigned_id - 0x100) >> 1;
}
static uint32_t
can_decode_nodeid(int nodeid)
{
return (nodeid << 1) + 0x100;
}
static void
can_process_query_unassigned(uint32_t id, uint32_t len, uint8_t *data)
{
if (canbus_assigned_id)
return;
uint8_t send[8];
send[0] = CANBUS_RESP_NEED_NODEID;
memcpy(&send[1], canbus_uuid, sizeof(canbus_uuid));
// Send with retry
for (;;) {
int ret = canbus_send(id, len, data);
int ret = canbus_send(CANBUS_ID_ADMIN_RESP, 7, send);
if (ret >= 0)
return;
}
}
static void
can_process_ping(uint32_t id, uint32_t len, uint8_t *data)
can_id_conflict(void)
{
canbus_send_blocking(canbus_assigned_id + 1, 0, NULL);
canbus_assigned_id = 0;
canbus_set_filter(canbus_assigned_id);
shutdown("Another CAN node assigned this ID");
}
static void
can_process_reset(uint32_t id, uint32_t len, uint8_t *data)
can_process_set_nodeid(uint32_t id, uint32_t len, uint8_t *data)
{
uint32_t reset_id = data[0] | (data[1] << 8);
if (reset_id == canbus_assigned_id)
canbus_reboot();
}
static void
can_process_uuid(uint32_t id, uint32_t len, uint8_t *data)
{
if (canbus_assigned_id)
if (len < 8)
return;
canbus_send_blocking(CANBUS_ID_UUID_RESP, sizeof(canbus_uuid), canbus_uuid);
}
static void
can_process_set_id(uint32_t id, uint32_t len, uint8_t *data)
{
// compare my UUID with packet to check if this packet mine
if (memcmp(&data[2], canbus_uuid, sizeof(canbus_uuid)) == 0) {
canbus_assigned_id = data[0] | (data[1] << 8);
canbus_set_filter(canbus_assigned_id);
uint32_t newid = can_decode_nodeid(data[7]);
if (can_check_uuid(id, len, data)) {
if (newid != canbus_assigned_id) {
canbus_assigned_id = newid;
canbus_set_filter(canbus_assigned_id);
}
} else if (newid == canbus_assigned_id) {
can_id_conflict();
}
}
// Handle an "admin" command
static void
can_process(uint32_t id, uint32_t len, uint8_t *data)
{
if (id == canbus_assigned_id) {
if (len)
can_process_data(id, len, data);
else
can_process_ping(id, len, data);
} else if (id == CANBUS_ID_UUID) {
if (len)
can_process_reset(id, len, data);
else
can_process_uuid(id, len, data);
} else if (id==CANBUS_ID_SET) {
can_process_set_id(id, len, data);
if (!len)
return;
switch (data[0]) {
case CANBUS_CMD_QUERY_UNASSIGNED:
can_process_query_unassigned(id, len, data);
break;
case CANBUS_CMD_SET_NODEID:
can_process_set_nodeid(id, len, data);
break;
}
}
@ -172,6 +180,19 @@ canbus_notify_rx(void)
sched_wake_task(&canbus_rx_wake);
}
static uint8_t receive_buf[192], receive_pos;
DECL_CONSTANT("RECEIVE_WINDOW", ARRAY_SIZE(receive_buf));
static void
can_process_data(uint32_t id, uint32_t len, uint8_t *data)
{
int rpos = receive_pos;
if (len > sizeof(receive_buf) - rpos)
len = sizeof(receive_buf) - rpos;
memcpy(&receive_buf[rpos], data, len);
receive_pos = rpos + len;
}
void
canbus_rx_task(void)
{
@ -185,7 +206,12 @@ canbus_rx_task(void)
int ret = canbus_read(&id, data);
if (ret < 0)
break;
can_process(id, ret, data);
if (id && id == canbus_assigned_id)
can_process_data(id, ret, data);
if (id && id == canbus_assigned_id + 1)
can_id_conflict();
else if (id == CANBUS_ID_ADMIN)
can_process(id, ret, data);
}
// Check for a complete message block and process it
@ -209,14 +235,19 @@ DECL_TASK(canbus_rx_task);
* Setup and shutdown
****************************************************************/
void
command_get_canbus_id(uint32_t *args)
{
sendf("canbus_id canbus_uuid=%.*s canbus_nodeid=%u"
, sizeof(canbus_uuid), canbus_uuid, can_get_nodeid());
}
DECL_COMMAND_FLAGS(command_get_canbus_id, HF_IN_SHUTDOWN, "get_canbus_id");
void
canbus_set_uuid(void *uuid)
{
memcpy(canbus_uuid, uuid, sizeof(canbus_uuid));
canbus_notify_rx();
// Send initial message
can_process_uuid(0, 0, NULL);
}
void

6
src/generic/canbus.h
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@ -3,16 +3,14 @@
#include <stdint.h> // uint32_t
#define CANBUS_ID_UUID 0x321
#define CANBUS_ID_SET 0x322
#define CANBUS_ID_UUID_RESP 0x323
#define CANBUS_ID_ADMIN 0x3f0
#define CANBUS_ID_ADMIN_RESP 0x3f1
#define CANBUS_UUID_LEN 6
// callbacks provided by board specific code
int canbus_read(uint32_t *id, uint8_t *data);
int canbus_send(uint32_t id, uint32_t len, uint8_t *data);
void canbus_set_filter(uint32_t id);
void canbus_reboot(void);
// canbus.c
void canbus_notify_tx(void);

28
src/stm32/can.c
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@ -159,43 +159,35 @@ canbus_send(uint32_t id, uint32_t len, uint8_t *data)
return len;
}
#define CAN_FILTER_NUMBER 0
// Setup the receive packet filter
void
canbus_set_filter(uint32_t id)
{
uint32_t filternbrbitpos = 1 << CAN_FILTER_NUMBER;
/* Select the start slave bank */
SOC_CAN->FMR |= CAN_FMR_FINIT;
/* Initialisation mode for the filter */
SOC_CAN->FA1R = 0;
uint32_t idadmin = CANBUS_ID_UUID;
SOC_CAN->sFilterRegister[CAN_FILTER_NUMBER].FR1 = idadmin << (5 + 16);
SOC_CAN->sFilterRegister[CAN_FILTER_NUMBER].FR2 = id << (5 + 16);
uint32_t mask = CAN_RI0R_STID | CAN_TI0R_IDE | CAN_TI0R_RTR;
SOC_CAN->sFilterRegister[0].FR1 = CANBUS_ID_ADMIN << CAN_RI0R_STID_Pos;
SOC_CAN->sFilterRegister[0].FR2 = mask;
SOC_CAN->sFilterRegister[1].FR1 = (id + 1) << CAN_RI0R_STID_Pos;
SOC_CAN->sFilterRegister[1].FR2 = mask;
SOC_CAN->sFilterRegister[2].FR1 = id << CAN_RI0R_STID_Pos;
SOC_CAN->sFilterRegister[2].FR2 = mask;
/* Identifier list mode for the filter */
SOC_CAN->FM1R = filternbrbitpos;
/* 32-bit scale for the filter */
SOC_CAN->FS1R = filternbrbitpos;
SOC_CAN->FS1R = (1<<0) | (1<<1) | (1<<2);
/* FIFO 0 assigned for the filter */
SOC_CAN->FFA1R = 0;
/* Filter activation */
SOC_CAN->FA1R = filternbrbitpos;
SOC_CAN->FA1R = (1<<0) | (id ? (1<<1) | (1<<2) : 0);
/* Leave the initialisation mode for the filter */
SOC_CAN->FMR &= ~CAN_FMR_FINIT;
}
void
canbus_reboot(void)
{
NVIC_SystemReset();
}
// This function handles CAN global interrupts
void
CAN_IRQHandler(void)
@ -292,7 +284,7 @@ can_init(void)
;
/*##-2- Configure the CAN Filter #######################################*/
canbus_set_filter(CANBUS_ID_SET);
canbus_set_filter(0);
/*##-3- Configure Interrupts #################################*/
armcm_enable_irq(CAN_IRQHandler, CAN_RX0_IRQn, 0);