wifi-tally_Oostendam/nodemcu-firmware/app/modules/am2320.c

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2021-09-27 19:52:27 +00:00
/*
* app/modules/am2320.c
*
* Copyright (c) 2016 Henk Vergonet <Henk.Vergonet@gmail.com>
*
* 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 2 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, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "module.h"
#include "lauxlib.h"
#include "platform.h"
#include "lwip/udp.h"
#include <errno.h>
static const uint32_t am2320_i2c_id = 0;
static const uint8_t am2320_i2c_addr = 0xb8 >> 1;
static uint16_t crc16(uint8_t *ptr, unsigned int len)
{
uint16_t crc =0xFFFF;
uint8_t i;
while(len--) {
crc ^= *ptr++;
for(i=0;i<8;i++) {
if(crc & 0x01) {
crc >>= 1;
crc ^= 0xA001;
} else {
crc >>= 1;
}
}
}
return crc;
}
/* make sure buf has lenght len+2 in order to accommodate for extra bytes */
static int _read(uint32_t id, void *buf, uint8_t len, uint8_t off)
{
int i;
uint8_t *b = (uint8_t *)buf;
uint16_t crc;
// step 1: Wake sensor
platform_i2c_send_start(id);
platform_i2c_send_address(id, am2320_i2c_addr, PLATFORM_I2C_DIRECTION_TRANSMITTER);
os_delay_us(800);
platform_i2c_send_stop(id);
// step 2: Send read command
platform_i2c_send_start(id);
platform_i2c_send_address(id, am2320_i2c_addr, PLATFORM_I2C_DIRECTION_TRANSMITTER);
platform_i2c_send_byte(id, 0x03);
platform_i2c_send_byte(id, off);
platform_i2c_send_byte(id, len);
platform_i2c_send_stop(id);
// step 3: Read the data
os_delay_us(1500);
platform_i2c_send_start(id);
platform_i2c_send_address(id, am2320_i2c_addr, PLATFORM_I2C_DIRECTION_RECEIVER);
os_delay_us(30);
for(i=0; i<len+2; i++)
b[i] = platform_i2c_recv_byte(id,1);
crc = platform_i2c_recv_byte(id,1);
crc |= platform_i2c_recv_byte(id,0) << 8;
platform_i2c_send_stop(id);
if(b[0] != 0x3 || b[1] != len)
return -EIO;
if(crc != crc16(b,len+2))
return -EIO;
return 0;
}
static int am2320_setup(lua_State* L)
{
int ret;
struct {
uint8_t cmd;
uint8_t len;
uint16_t model;
uint8_t version;
uint32_t id;
} nfo;
os_delay_us(1500); // give some time to settle things down
ret = _read(am2320_i2c_id, &nfo, sizeof(nfo)-2, 0x08);
if(ret)
return luaL_error(L, "transmission error");
lua_pushinteger(L, ntohs(nfo.model));
lua_pushinteger(L, nfo.version);
lua_pushinteger(L, ntohl(nfo.id));
return 3;
}
static int am2320_read(lua_State* L)
{
int ret;
struct {
uint8_t cmd;
uint8_t len;
uint16_t rh;
uint16_t temp;
} nfo;
ret = _read(am2320_i2c_id, &nfo, sizeof(nfo)-2, 0x00);
if(ret)
return luaL_error(L, "transmission error");
ret = ntohs(nfo.temp);
if(ret & 0x8000)
ret = -(ret & 0x7fff);
lua_pushinteger(L, ntohs(nfo.rh));
lua_pushinteger(L, ret);
return 2;
}
LROT_BEGIN(am2320, NULL, 0)
LROT_FUNCENTRY( read, am2320_read )
LROT_FUNCENTRY( setup, am2320_setup )
LROT_END(am2320, NULL, 0)
NODEMCU_MODULE(AM2320, "am2320", am2320, NULL);