Beyond the LED

I worked with Sam to build a circuit board with an operational amplifier! We used a LM386.

This is the schematic we breadboarded from.

This is the schematic we breadboarded from. There are many other schematics to work from in the LM386 datasheet.



The sound quality is far from desirable. Michelle and Eric Rosenthal helped us modify the circuit to smooth the signal. We’ll breadboard the new design and try out the sound quality later.

Schematic and board design from the new design.

Schematic and board design.


Queue entrance music


I ended up spending a lot of time this week doing more market research, wireframing, and redesigning the app. There’s a myriad of customizable productivity apps that have similar features. Productivity was never my objective for the application though; I’d rather enable playful and creative customizations. My redesign focus on communication between people and content sharing and allowing this to be customized like IFTTT.

List of apps 

Checkmark (iOS)

DO button, DO camera, DO Notes from IFTTT (iOS)

Agent (android)

Trigger (android)



create new

create new

I’ve started on the front-end dev of the app with HTML/CSS/jQuery Mobile.

Next up

Finish up front-end dev

Plugins! Plugins! Plugins!






Hello LED


The first time I tried using the GSM module to send a text, I made the dumb mistake of not turning on the module. So it worked this time. I used the code that Benedetta had emailed us.

Sending SMS from GSM module.

Sending SMS from GSM module.

A modest next step: turn on a LED with a text. For now, I’m able to receive texts by sending them through the GSM module with CoolTerm, but I can’t receive any messages on the GSM module. I’ll need to figure out how to receive a message, match it, then change the LED pin output to HIGH.


I attempted again with the white GSM module. I can read SMS with CoolTerm now, but there seems to be a long delay. It takes a few seconds for the messages to show. If I use the command AT+CMGL=”ALL”, only the first part of the first message would display correctly. The rest of the messages are in gibberish. I tried changing the delay that follows Serial.write(inChar); in the code. But this didn’t help.

Reading SMS in CoolTerm.

Reading SMS in CoolTerm.

I also tried to turn the LED on by texting I, and turning it off by texting O. After about 10 secs of texting I, the LED would turn on. But typing O did not work. Also if I change the letter in the code from I to O, the LED would not turn on. Another issue I had was that after testing with my SIM card for a while, I wouldn’t be able to read anymore SMS on that card though I was still able to send SMS out. I had to switch to another SIM card to continue testing and reading SMS.

This is how it worked when I text “I” to turn on the LED:

Here’s the code:


Is Serial.write(mySerial.(read)) writing +CMTI: “SM”,sms# each time? Perhaps this is why typing I would turn the LED on – because +CMTI contains the letter I. If this is the case, what is an effective way to check for +CMTI: “SM”,sms#, mySerial.print() the AT commands for reading SMS, skip through the metadata for the SMS, and read the actual SMS message?