139 lines
3.5 KiB
C
139 lines
3.5 KiB
C
/*
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* app/modules/am2320.c
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*
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* Copyright (c) 2016 Henk Vergonet <Henk.Vergonet@gmail.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "module.h"
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#include "lauxlib.h"
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#include "platform.h"
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#include "lwip/udp.h"
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#include <errno.h>
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static const uint32_t am2320_i2c_id = 0;
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static const uint8_t am2320_i2c_addr = 0xb8 >> 1;
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static uint16_t crc16(uint8_t *ptr, unsigned int len)
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{
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uint16_t crc =0xFFFF;
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uint8_t i;
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while(len--) {
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crc ^= *ptr++;
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for(i=0;i<8;i++) {
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if(crc & 0x01) {
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crc >>= 1;
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crc ^= 0xA001;
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} else {
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crc >>= 1;
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}
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}
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}
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return crc;
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}
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/* make sure buf has lenght len+2 in order to accommodate for extra bytes */
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static int _read(uint32_t id, void *buf, uint8_t len, uint8_t off)
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{
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int i;
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uint8_t *b = (uint8_t *)buf;
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uint16_t crc;
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// step 1: Wake sensor
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platform_i2c_send_start(id);
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platform_i2c_send_address(id, am2320_i2c_addr, PLATFORM_I2C_DIRECTION_TRANSMITTER);
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os_delay_us(800);
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platform_i2c_send_stop(id);
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// step 2: Send read command
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platform_i2c_send_start(id);
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platform_i2c_send_address(id, am2320_i2c_addr, PLATFORM_I2C_DIRECTION_TRANSMITTER);
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platform_i2c_send_byte(id, 0x03);
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platform_i2c_send_byte(id, off);
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platform_i2c_send_byte(id, len);
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platform_i2c_send_stop(id);
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// step 3: Read the data
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os_delay_us(1500);
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platform_i2c_send_start(id);
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platform_i2c_send_address(id, am2320_i2c_addr, PLATFORM_I2C_DIRECTION_RECEIVER);
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os_delay_us(30);
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for(i=0; i<len+2; i++)
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b[i] = platform_i2c_recv_byte(id,1);
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crc = platform_i2c_recv_byte(id,1);
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crc |= platform_i2c_recv_byte(id,0) << 8;
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platform_i2c_send_stop(id);
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if(b[0] != 0x3 || b[1] != len)
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return -EIO;
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if(crc != crc16(b,len+2))
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return -EIO;
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return 0;
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}
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static int am2320_setup(lua_State* L)
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{
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int ret;
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struct {
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uint8_t cmd;
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uint8_t len;
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uint16_t model;
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uint8_t version;
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uint32_t id;
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} nfo;
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os_delay_us(1500); // give some time to settle things down
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ret = _read(am2320_i2c_id, &nfo, sizeof(nfo)-2, 0x08);
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if(ret)
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return luaL_error(L, "transmission error");
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lua_pushinteger(L, ntohs(nfo.model));
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lua_pushinteger(L, nfo.version);
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lua_pushinteger(L, ntohl(nfo.id));
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return 3;
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}
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static int am2320_read(lua_State* L)
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{
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int ret;
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struct {
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uint8_t cmd;
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uint8_t len;
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uint16_t rh;
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uint16_t temp;
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} nfo;
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ret = _read(am2320_i2c_id, &nfo, sizeof(nfo)-2, 0x00);
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if(ret)
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return luaL_error(L, "transmission error");
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ret = ntohs(nfo.temp);
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if(ret & 0x8000)
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ret = -(ret & 0x7fff);
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lua_pushinteger(L, ntohs(nfo.rh));
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lua_pushinteger(L, ret);
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return 2;
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}
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LROT_BEGIN(am2320, NULL, 0)
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LROT_FUNCENTRY( read, am2320_read )
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LROT_FUNCENTRY( setup, am2320_setup )
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LROT_END(am2320, NULL, 0)
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NODEMCU_MODULE(AM2320, "am2320", am2320, NULL);
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