Griff and Griff Mini
384kHz USB microphones for bat detection and recording
Pipistrelles, Serotines, Noctules, Brandt's bats and Whiskered bats.
Recorded on 23rd May 2026 using Griff, "Bat Detector" for iOS and a 2019 model iPad
Recorded on 23rd May 2026 using Griff, "Bat Detector" for iOS and a 2019 model iPad
REFLASHING YOUR DEVICE FIRMWARE - download firmware from link on ASSEMBLY page
This is version 10.01 of pipistrelle-usb-microphone.uf2. First, plug a USB to micro USB cable into your desktop computer. Next squeeze the white button on the back of Griff, and keep it squeezed as you plug the micro USB cable into Griff. Griff temporarily becomes a flash drive called RPI-RP2 - drag the .uf2 file onto this flash drive, and the on-device firmware will be rewritten and the Griff will reboot, running the new firmware.
This is version 10.01 of pipistrelle-usb-microphone.uf2. First, plug a USB to micro USB cable into your desktop computer. Next squeeze the white button on the back of Griff, and keep it squeezed as you plug the micro USB cable into Griff. Griff temporarily becomes a flash drive called RPI-RP2 - drag the .uf2 file onto this flash drive, and the on-device firmware will be rewritten and the Griff will reboot, running the new firmware.
So why is a bat detecting microphone called Griff?
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Griff is named after a superstar Noctule, the mealworm-munching star of the TV campaign for a major Hollywood movie featuring the dashing Robert Pattinson in a cracking Bat Suit. But beyond that he was the best bat that ever was. He was an educational bat looked after by the lovely Amy, he charmed hundreds of visitors to the launch of "On a Wing and a Prayer" at St. Sampson's church Cricklade, and after a very happy and rich life he passed away in July 2025. Griff will never be forgotten, and we all loved that guy.
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Griff and Griff Mini are by MILES the easiest devices to build.
Griff and Griff Mini are powered by the Raspberry Pi Pico, and are extremely inexpensive - either design can be built for as little as £5 per device when building 10-off. Griff Mini is a more "sensible" shape and features mounting holes at the corners to simplify attaching permanently to a surface or to a hat. Griff, the original design, is just too cute for words and features an integral brooch pin for instant wearability. Functionally and electrically the two designs are identical, but Griff Mini has a somewhat less cramped layout, and as a result has the potential to deliver slightly cleaner recordings, but any differences will be negligible.
Blank PCBs and solder paste stencils are available from PCBWay at a cost of $5 for 10 PCBs, $10 for the solder paste stencil, plus shipping, which is typically additional $24 for shipping to UK : https://www.pcbway.com/project/shareproject/Griff_Mini_d4d7cbaa.html
The electronic components needed to build Griff and Griff Mini are available direct from DigiKey : the DigiKey link is on the PCBWay page, along with a link to the brooch pin I use on the back to make the designs wearable.
Note that your build costs can be dramatically reduced if you buy Raspberry Pi Pico clones from AliExpress, rather than genuine Raspberry Pi devices. You can save around £2 per assembled device by taking this route : https://www.aliexpress.com/w/wholesale-raspberry-pi-pico.html, and these clones offer more flexibility in that you can choose a USB-C connector rather than just micro USB, but the USB-C implementation leaves a lot to be desired, I find it best to stick to micro USB.
The build for these designs is very easy. The only fiddly component is the Syntiant microphone chip which is very small, and you need to be careful when assembling that you have not accidentally squeegeed solder paste into the acoustic hole through the PCB. Build time per Griff is well under 10 minutes once you are in the swing. I offer as proof an 8 minute build video for a Griff Mini of the current design. It is presented without edits, so every ham-fisted, time--consuming misstep and dropped / forgotten component is included - enjoy 😀
Griff and Griff Mini are powered by the Raspberry Pi Pico, and are extremely inexpensive - either design can be built for as little as £5 per device when building 10-off. Griff Mini is a more "sensible" shape and features mounting holes at the corners to simplify attaching permanently to a surface or to a hat. Griff, the original design, is just too cute for words and features an integral brooch pin for instant wearability. Functionally and electrically the two designs are identical, but Griff Mini has a somewhat less cramped layout, and as a result has the potential to deliver slightly cleaner recordings, but any differences will be negligible.
Blank PCBs and solder paste stencils are available from PCBWay at a cost of $5 for 10 PCBs, $10 for the solder paste stencil, plus shipping, which is typically additional $24 for shipping to UK : https://www.pcbway.com/project/shareproject/Griff_Mini_d4d7cbaa.html
The electronic components needed to build Griff and Griff Mini are available direct from DigiKey : the DigiKey link is on the PCBWay page, along with a link to the brooch pin I use on the back to make the designs wearable.
Note that your build costs can be dramatically reduced if you buy Raspberry Pi Pico clones from AliExpress, rather than genuine Raspberry Pi devices. You can save around £2 per assembled device by taking this route : https://www.aliexpress.com/w/wholesale-raspberry-pi-pico.html, and these clones offer more flexibility in that you can choose a USB-C connector rather than just micro USB, but the USB-C implementation leaves a lot to be desired, I find it best to stick to micro USB.
The build for these designs is very easy. The only fiddly component is the Syntiant microphone chip which is very small, and you need to be careful when assembling that you have not accidentally squeegeed solder paste into the acoustic hole through the PCB. Build time per Griff is well under 10 minutes once you are in the swing. I offer as proof an 8 minute build video for a Griff Mini of the current design. It is presented without edits, so every ham-fisted, time--consuming misstep and dropped / forgotten component is included - enjoy 😀
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A finished USB-C Griff Mini, assembled as a wearable device with integrated brooch pin
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When using Griff as a USB microphone for bat detection and recording on a mobile device, the recommended apps are Android : Bat Gizmo (by John Mears) on the left, and on the right for iPhone and iPad : Bat Detector (by Phil Atkin - that's me by the way 😀 👍)
Bat Detector features real-time time expansion along with auto-tuned heterodyne detection, and saves a folder of sonograms along with your 384kHz WAV recordings for rapid visual scans. Bat Gizmo features twin heterodyne detection, manually tuned. Both apps embed geolocation into their WAV files using GUANO metadata, and generate recordings optimised for the BTO Acoustic Pipeline. |
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On the left is the help file for Bat Detector for iPhone and iPad. This PDF is in fact embedded witin the app, but it's here because people seem to have trouble finding it :)
Look in - Files -> On my iPhone -> Bat Detector |