MPL3115A2 Troubleshooting

Hello there!

I posted something similar on this a while back, but I abandoned the project then. Arrogant as I am, I am back at the project again, which is going (slightly) better. I am building a weatherstation using:

• DHT22 for Temp and RH,
  -TSL2561 for Light Measurements
  -MPL3115A2 for Pressure
  
  

Basically, I have the light sensor and Temp sensor working, but I can't get the pressure board to go

The configuration is:

• DHT22 @ B5,
  -TSL @ B6 + B7,
  -MPL @ B4,A8
  
  

I keep getting TIMEOUT errors, but the power and ground work for the TSL

Can someone help me!

Cheers,

Scott

Pico or Standard board? Did you try the devices separately using the examples provided by espruino.com/Modules?

-

This is almost certainly because you need pullup resistors on the SDA and SCL data wires. Pretty much all I2C devices need it. Some modules have them pre-installed, but some don't

• Pico
  
• I tried them all separately, using the modules provided on the website
  
• I purchased all my gear from adafruit, on the breakout boards (which come with resistors?)
  
• Not sure what's going wrong here..
  // Here's the error message:
  "Uncaught InternalError: Timeout on I2C Write Transmit Mode 2
  at line 1 col 41
  ...eTo(C.MPL3115A2_ADDRESS,reg);var d=this.i2c.readFrom(C.MPL31...
  ^
  in function "readS16" called from line 1 col 67
  ...L3115A2_REGISTER_CAL_A0_MSB)/8;this.b1=this.readS16(C.MPL311...
  ^
  in function "MPL3115A2" called from line 1 col 19
  new MPL3115A2(_i2c)
  ^
  in function "connect" called from line 1 col 38
  var mpl = require("mpl").connect(I2C3);
  ^
  Uncaught Error: Field or method "getAltitude" does not already exist, and can't create it on undefined
  at line 1 col 4
  mpl.getAltitude(function(x) {
  ^
  =undefined
  > "
  

The I2C timeout is when it's not able to communicate with the module over I2C.

So...

• Did you set up I2C3 with I2C3.setup(...)?
  
• Is it powered properly? Looks like it needs connecting up with Vin not 3.3v.
  
  

Finally, try adding some 10k pull-up resistors. the Adafruit page doesn't mention that it has them and I think some Arduino boards to have them on so they may have left them off of the adaptor board?

Also, are SDA and SCL actually connected up to the right places? They could have got crossed over.

• SDA and SCL are hooked up in the right spots,

• It's running on 5v to Vin

• I don't have any resistors, so I'll run to the store and pick some up. Would the DHT22 also require those? (It works for me...sometimes, but it's finnicky)

When boards have the resistors, then they usually have a pin or solder jumper to enable them, because only on resistor is needed for each line... (otherwise, the behavior would be dependent on the number of connected devices to a point where either drivers could not fan the load anymore and signals become useless.... like: if too many people hold the rope down or up, no single individual would be able to raise or lower it! Espruino (STM MC) has a pull-down/pull-up option on the pins, but in this case it is too weak for I2C: 30..40K vs 4K7 (even though 4K7 works for most cases, the answer for 'What value the resistor should have?' is not that simple). --- How to get something tested right away until you get your resistors? Do you have some unused GPIO ports left? Configure 2..4 of them as pinMode(,"input_pullup") and connect them to SCL and SDA - of course for each individually - that gives you at least some pulling and may already help... ;-) --- This is not the 'production' solution... but Apollo13 parents still a lot of creativity!

Some error messages get a bit convoluted on bubbling up, especially the uncaught / unexpected ones, because it is expected that under normal circumstances the hardware is properly setup - no offense here, the culprit could just be the well known faulty breadboard contact - and wasting space to bubble up all variations is a waste of space... especially when there is a stack trace available as in Espruino (thank you @Gordon... robust and concise software design and implementation).

I think the DHT22 should be ok without them - it's not I2C. The DHT22 module got updated this week though, so it might be a bit better?