MirrorSave
/
nodemcu-firmware
mirror of https://github.com/nodemcu/nodemcu-firmware.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Correct integer types in BMP085 driver (#3070) 

* BMP085 pressure sensor: fix temperature value data type

the data type for t (U_T) should be long according to the BMP085
datasheet (rev. 1.2, section 3.5). values over 32767 can indeed occur,
and in my case lead to a wrong value for the temperature (and
consequently also pressure).

note: this problem only occurs above a certain temperature (exact
value depends on the calibration, but I assume somewhere around 26°C).

* BMP085 pressure sensor: adapt data types and calculation

this adapts the data types and calculation to be consistent with the
datasheet (rev. 1.2, section 3.5). while I did not notice any issues,
using the wrong data types could trigger edge cases.
This commit is contained in:
Andreas Müller 2020-04-24 15:37:48 +02:00 committed by Marcel Stör
parent c8c90fe4e1
commit 95fc8b14b3
1 changed files with 11 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
app/modules/bmp085.c
View File

@ -64,8 +64,8 @@ static int bmp085_setup(lua_State* L) {
return 0;
}
static uint32_t bmp085_temperature_raw_b5(void) {
int16_t t, X1, X2;
static int32_t bmp085_temperature_raw_b5(void) {
int32_t t, X1, X2;
platform_i2c_send_start(bmp085_i2c_id);
platform_i2c_send_address(bmp085_i2c_id, bmp085_i2c_addr, PLATFORM_I2C_DIRECTION_TRANSMITTER);
@ -76,7 +76,7 @@ static uint32_t bmp085_temperature_raw_b5(void) {
// Wait for device to complete sampling
os_delay_us(4500);
t = r16(bmp085_i2c_id, 0xF6);
t = r16u(bmp085_i2c_id, 0xF6);
X1 = ((t - bmp085_data.AC6) * bmp085_data.AC5) >> 15;
X2 = (bmp085_data.MC << 11)/ (X1 + bmp085_data.MD);
@ -138,7 +138,8 @@ static int bmp085_lua_pressure_raw(lua_State* L) {
static int bmp085_lua_pressure(lua_State* L) {
uint8_t oss = 0;
int32_t p;
int32_t X1, X2, X3, B3, B4, B5, B6, B7;
int32_t X1, X2, X3, B3, B5, B6;
uint32_t B4, B7;
if (lua_isnumber(L, 1)) {
oss = luaL_checkinteger(L, 1);
@ -158,9 +159,13 @@ static int bmp085_lua_pressure(lua_State* L) {
X1 = ((int32_t)bmp085_data.AC3 * B6) >> 13;
X2 = ((int32_t)bmp085_data.B1 * ((B6 * B6) >> 12)) >> 16;
X3 = (X1 + X2 + 2) >> 2;
B4 = ((int32_t)bmp085_data.AC4 * (X3 + 32768)) >> 15;
B4 = ((uint32_t)bmp085_data.AC4 * (X3 + 32768)) >> 15;
B7 = (p - B3) * (50000 / (1 << oss));
p = (B7 / B4) << 1;
if (B7 < 0x80000000) {
p = (B7 * 2) / B4;
} else {
p = (B7 / B4) * 2;
}
X1 = (p >> 8) * (p >> 8);
X1 = (X1 * 3038) >> 16;
X2 = (-7357 * p) >> 16;