readBytes method
wakatanka opened this issue · comments
Hi, i'm trying to read temperature from a sensor (sht21) with a raspberry pi, here is my working code:
var i2c = require('i2c');
var address = 0x40;
var wire = new i2c(address, {device: '/dev/i2c-1',debug: false});
wire.scan(function(err, data) {
// result contains an array of addresses
if (err !== null) {
console.log('error scan: ' + err);
} else {
console.log("scan data: "+data);
}
});
wire.writeByte(0xF3, function(err) {
if (err !== null) {
console.log("error write: " + err);
} else {
console.log("write ok");
}
});
wire.readByte(function(err, res) {
if (err !== null) {
console.log("error readByte: " + err);
} else {
console.log(res);
}
})
this works flawless, but i need to read the first 3 bytes to get all data, so i will use readbytes method with this code:
wire.readBytes(0x00, 3, function(err, res) {
// result contains a buffer of bytes
//var value = res.readUInt8(0);
if (err !== null) {
console.log("readBytes: " + err);
} else {
console.log(res);
}
});
but it gives me an error. Probably i didn't understand what i have to pass as command parameter.
I think you want to do wire.readBytes(0xF3, 3, function ....
The initial write that you're doing is the command byte. That's telling your device that you want to receive 3 bytes of data.
Hi @wakatanka I'm also using the sh21t sensor with a raspberry pi. Have a look at pull request #35 from @bbx10 which contains a fix to read bytes without sending the command/register parameter. This fix also works for sh21t sensor.
