This blog details the circuitry and PCB layout of my custom Booster Pack to monitor 8 hazardous gasses and ultraviolet light. I added some active circuitry to filter the CO2 sensor PWM output since my last blog. This is a 4-pole low-pass Butterworth filter with a cut-off frequency of 10 Hz. (The signal is 1 KHz PWM).

MQx_Booster

The PCB is laid out to fit on the   https://www.element14.com/community/view-product.jspa?fsku=2473128&nsku=41Y9541&COM=noscriptMSP-EXP432P401R MCU as a normal Booster Pack The pins it uses are carefully selected to not interfere with pins used by the  430BOOST-SHARP96430BOOST-SHARP96 LCD or the CC31000ModBoost WiFi nodule

The following table shows the Booster Pack pins used by each of the modules in the kit plus my custom Booster Pack. I have highlighted the modules/pins I will be using. Note there are lots of conflicts if you want to use all of these modules together. They can often be resolved with jumpers on the cards, but the process must be thought through in detail. Even with the modules I have selected, there are a couple of conflicts which I need to resolve. I will permanently enable the LCD, so it doesn't need a control pin and display COM inversion pin will be disconnected and not used. In the end, my project will use 34 of the 40 pins - all of J1 and J2 plus most of J3 and J4.

Booster432P401RMCUSHARP LCDCC3100ModBoost BoostXLBoostSense1CC2650BLEDLP7970ABPMQ_booster
J1-1+3.3V+3.3V+3.3V+3.3V+3.3V+3.3V+3.3V+3.3V+3.3V+3.3V
J1-2Analog InA15P6.0LCD ControlLED9MRDY
J1-3UART RXUART RXP3.2UART RXTXD
J1-4UART TXUART TXP3.3UART TXRXD
J1-5GPIOGPIO 1P4.1LCD EnablenHibINT1LEDx
J1-6Analog InA10P4.3SPI CSLED1
J1-7SPI CLKSPI CLKP1.5SPI CLKSPI CLKLED2SPI CLKSPI CLK
J1-8GPIOGPIO 2P4.6Left Slide 2MAG INTSens0DIOIRQ
J1-9I2C SCLI2C SCLP4.5Left Slide 1I2C SCLSens1SPI CS
J1-10I2C SDAI2C SDAP4.4Left Slide 0I2C SDASens2EN
J2-1GNDGNDGNDGNDGNDGNDGNDGNDGNDGND
J2-2GPIOGPIOP2.5Ext COM InvertIRQSRDY
J2-3SPI CS WSPI CS WP3.0SPI CSSPI CSXout
J2-4GPIOGPIOP5.7
J2-5RSTRSTRSTnResetReset
J2-6SPI MOSISPI MOSIP1.6SPI SIMOSPI MOSILED4MOSIMOSI
J2-7SPI MISOSPI MISOP1.7SPI MISOLED3MISOMISO
J2-8SPI CS DSPI CS DP5.0Right Slide 2INT2Sens5DIO13LED
J2-9SPI CS OSPI CS OP5.2Right Slide 1TMP INTSens4LED
J2-10GPIOGPIOP3.6Right Slide 0OPT INTSens3LED
J3-1'+5V'+5V'+5V'+5V'+5V'+5V
J3-2GNDGNDGNDGNDGNDGNDGND
J3-3Analog In 3A14P6.1MQ-7
J3-4Analog In 4A13P4.0MQ-135
J3-5Analog In 5A11P4.2MQ-3
J3-6Analog In 6A9P4.4UV
J3-7Analog In 7A8P4.5CO2
J3-8Analog In 8A6P4.7
J3-9A10P5.4
J3-10A0P5.5
J4-1GPIOGPIOP2.7
J4-2GPIOGPIOP2.6
J4-3GPIOGPIOP2.4MQ7D
J4-4GPIOVREFP5.6UART CTS
J4-5GPIOGPIOP6.6UART RTS
J4-6GPIOGPIOP6.7nReset
J4-7GPIOGPIOP2.3NWP Log TX
J4-8GPIOGPIOP5.1WLAN Log TX
J4-9GPIOGPIOP3.5MQ135D
J4-10GPIOGPIOP3.7MQ3D

Hopefully this table will save some of the other contestants some work, although they will still need to check everything.

The PCB layout is shown below. It is intended to sit above the MCU, but below the LCD. The WiFi module will go below the MCU. The sensors will surround the LCD without increasing the width of the whole stack. This is because I have to mount three other instrument clusters on my arm beside this sensor stack.

MQx_BoosterLayout

Now that I am finally getting this card on order, I can start working on the radiation aspects of this project. I have already learned a lot with the research I have done on environmental gasses and environmental radiation work looks to be at least as involved.

 

All links to blogs related to this project can be found in the first blog here:

Safe and Sound - Invisible Hazardous Environmental Factors Monitoring System - blog 1