# RFID reader (WPI405) example code not working **URL:** \ **Category:** Support\ **Created:** [March 18, 2022, 12:05pm UTC](https://forums.pimoroni.com/t/rfid-reader-wpi405-example-code-not-working/19117 "2022-03-18T12:05:44Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Petr](https://avatars.discourse-cdn.com/v4/letter/p/ac8455/32.png) [@Petr](https://forums.pimoroni.com/u/Petr)\ **Post date:** [March 18, 2022, 12:05pm UTC](https://forums.pimoroni.com/t/rfid-reader-wpi405-example-code-not-working/19117/1 "2022-03-18T12:05:44Z")
Hi all, Just bought this card with two RFID tags and connected it to a brand new Pi Zero 2 w with a new install of PiOS (64). Information about how to use the card is a bit sparse and I tried the instructions here: [How to setup a Raspberry Pi RFID RC522 Chip - Pi My Life Up](https://pimylifeup.com/raspberry-pi-rfid-rc522/) without success. Just nothing either on the card (not even a LED saying it has power) no errors from the python code, and no response, read or write, from either of the two provided RFID tags. The card in the instructions is the previous version and has an SDA pin, where as this newer version has a NSS pin. I guessed that should be connected to gpio24 on the assumption it is a naming convention. Alternatively, could it be that I need to use 32bit PiOS? Any advice? Happy to wade through data sheets but if I don’t need to … P ---
**Author:** ![alphanumeric](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.pimoroni.com/alphanumeric/32/2729_2.png) [@alphanumeric](https://forums.pimoroni.com/u/alphanumeric)\ **Post date:** [March 18, 2022, 1:01pm UTC](https://forums.pimoroni.com/t/rfid-reader-wpi405-example-code-not-working/19117/2 "2022-03-18T13:01:32Z")
That’s a bit confusing? SDA GPIO 2, is i2c, and it is using SPI? Unless I’m missing something? The user manual says NSS (= SDA) [vma405\_a4v03.pdf (shopify.com)](https://cdn.shopify.com/s/files/1/0174/1800/files/vma405_a4v03.pdf?v=1623157366) ---
**Author:** ![Petr](https://avatars.discourse-cdn.com/v4/letter/p/ac8455/32.png) [@Petr](https://forums.pimoroni.com/u/Petr)\ **Post date:** [March 18, 2022, 1:44pm UTC](https://forums.pimoroni.com/t/rfid-reader-wpi405-example-code-not-working/19117/3 "2022-03-18T13:44:50Z")
That would explain the renaming. The RFID card (old version) has an SDA pin (labelled “SDA”) that the instructions say to connect to the pi’s pin 24 (not SDA). The new version of the RFID card does not have an SDA pin but does have a NSS pin. ---
**Author:** ![alphanumeric](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.pimoroni.com/alphanumeric/32/2729_2.png) [@alphanumeric](https://forums.pimoroni.com/u/alphanumeric)\ **Post date:** [March 18, 2022, 2:44pm UTC](https://forums.pimoroni.com/t/rfid-reader-wpi405-example-code-not-working/19117/4 "2022-03-18T14:44:52Z")
Keep in mind that (physical) pin 24 is GPIO 8 (BCM numbering) And that is SPI Chip Select 0. Make sure your on Pin 24 not GPIO 24. > **[SPI at Raspberry Pi GPIO Pinout](https://pinout.xyz/pinout/spi)** > > Raspberry Pi SPI pins ---
**Author:** ![Petr](https://avatars.discourse-cdn.com/v4/letter/p/ac8455/32.png) [@Petr](https://forums.pimoroni.com/u/Petr)\ **Post date:** [March 18, 2022, 4:58pm UTC](https://forums.pimoroni.com/t/rfid-reader-wpi405-example-code-not-working/19117/5 "2022-03-18T16:58:53Z")
Okay my fault; had swapped MISO and MOSI lines for some reason (it was a late one last night…). So can confirm that the WPI405 works with the instructions at > **[How to setup a Raspberry Pi RFID RC522 Chip](https://pimylifeup.com/raspberry-pi-rfid-rc522/)** > > Set up a RFID reader for the Pi. and that, where the site mentions SDA, it is now the NSS pin. P ---
**Author:** ![alphanumeric](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.pimoroni.com/alphanumeric/32/2729_2.png) [@alphanumeric](https://forums.pimoroni.com/u/alphanumeric)\ **Post date:** [March 18, 2022, 6:24pm UTC](https://forums.pimoroni.com/t/rfid-reader-wpi405-example-code-not-working/19117/6 "2022-03-18T18:24:58Z")
Nice to hear you got it working. Mistakes like that are easy to do. I’ve made my fair share of them.