---
title: "Project 121"
date: 2016-07-25
vim: nowrap
---

Project 121 is a rugged temperature logger for high heat environments. It uses
the ATtiny4 microcontroller with 32 bytes of ram and 512 bytes of flash
storage.


imagethumb:boards.png[Version 1 of the boards]
imagethumb:tinyavr.jpg[ATtiny4-TS8R microcontroller]

## Bill of Materials
--------------|----------------------------|--------------------------------------------------------------------------------------------------------------------|--------|-----------------|------------
Battery       | Tadiran TLH-5903           | <http://www.tadiran.com/pdf.php?id=TLH-5903>                                                                       | $12.01 | -55°C to +125°C | 3.0V - 3.6V
CPU           | ATtiny4-TS8R               | <http://www.atmel.com/images/atmel-8127-avr-8-bit-microcontroller-attiny4-attiny5-attiny9-attiny10_datasheet.pdf>  | $0.33  | -40°C to +125°C | 1.8V - 5.5V
temp0         | Silicon Labs Si7051-A20-IM | <http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7050-1-3-4-5-A20.pdf>                                   | $1.95  | -40°C to +125°C | 1.9V - 3.6V
temp1         | Silicon Labs Si7051-A20-IM | <http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7050-1-3-4-5-A20.pdf>                                   | $1.95  | -40°C to +125°C | 1.9V - 3.6V
rtc           | NXP PCA8565TS              | <http://www.nxp.com/documents/data_sheet/PCA8565.pdf>                                                              | $1.73  | -40°C to +125°C | 1.8V - 5.5V
analog switch | Diodes 74LVC1G3157         | <http://www.diodes.com/_files/datasheets/74LVC1G3157.pdf>                                                          | $0.37  | -40°C to +125°C | 1.65V - 5.5V
mem0          | ST M24M02-DWMN3TP/K        | <http://www.st.com/web/en/resource/technical/document/datasheet/DM00200595.pdf>                                    | $3.25  | -40°C to +125°C | 2.5V - 5.5V
mem1          | ST M24M02-DWMN3TP/K        | <http://www.st.com/web/en/resource/technical/document/datasheet/DM00200595.pdf>                                    | $3.25  | -40°C to +125°C | 2.5V - 5.5V
regulator     | TI TPS62230DRYT            | <http://www.ti.com/lit/ds/symlink/tps62230.pdf>                                                                    | $1.69  | -40°C to +125°C | 2.05V - 6V

TOTAL $26.53