Timeline for Issue sharing MISO with multiple RC522 RFID Readers
Current License: CC BY-SA 3.0
19 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Mar 19, 2018 at 3:35 | history | protected | CommunityBot | ||
| Sep 30, 2017 at 22:03 | comment | added | Marko Grujic | I don't have reputation to comment but I want to thank Michael. His solution is perfect, I was stuck for days. So, Multi RFID with software SPI works as a charm! | |
| Aug 21, 2017 at 22:43 | answer | added | Rodrigo Franco | timeline score: 2 | |
| May 10, 2017 at 0:12 | answer | added | Michael | timeline score: 4 | |
| Sep 23, 2016 at 2:55 | comment | added | Brennan Cheung | Where you able to figure anything out? I'm having a similar issue. arduino.stackexchange.com/questions/29494/… Sounds like it might be the same type of problem. | |
| Dec 13, 2015 at 13:52 | history | tweeted | twitter.com/StackArduino/status/676037083044192257 | ||
| Dec 2, 2015 at 9:10 | comment | added | frarugi87 | @jwpat7 actually the problem is not on the arduino side, but on the device side. You are sending 5V on pins which can support only 3.8V if I remember correctly (Vcc + 0.5). So you are working out of specs. If they happen to work even in these conditions ok, but you can expect strange behaviors from this setup. IMHO the first thing to do is to lower the 5V inputs to 3.3. Even a passive voltage divider can work. Then, when you are sure that you are working following the specs, you can modify something else | |
| Dec 2, 2015 at 2:12 | answer | added | bigjosh | timeline score: 3 | |
| Dec 2, 2015 at 0:50 | comment | added | Jesse Mount | The one I have looks like the red one, but it's blue. 'Image Here'. I'm sure it's using SPI as I have no trouble communicating with the Serial from the RC522. The only issue i'm having is using more than 1. If there is another RC522 plugged into the MISO line, it causes a communication error and prevents any data from being printed out on the Serial from either device, regardless of if the 2nd one is initiated or not, or at which logic state the SS pins are set at. | |
| Dec 2, 2015 at 0:06 | comment | added | James Waldby - jwpat7 | Jesse Mount, perhaps look at the May 06, 2014 11:34 pm post on raspberrypi.org/forums and indicate here if your RFC22's match one of the 2 shown there (3rd link's bad). That post also tells how to verify protocol is SPI etc. Note, that thread implies your hookup diagram should be ok but if desperate you could use a multiplexer, eg a 74LS153 would let you select 1 line of 4 | |
| Dec 1, 2015 at 22:35 | history | edited | Jesse Mount | CC BY-SA 3.0 |
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| Dec 1, 2015 at 20:14 | comment | added | Majenko | @jwpat7 Incidentally, I can find no mention of tri-state on MISO in the MFRC522 datasheet. Doesn't mean there isn't, but also doesn't mean there is... | |
| Dec 1, 2015 at 20:13 | comment | added | James Waldby - jwpat7 | @Majenko, thanks, that's what I should have meant, regarding SPI. Was thinking of IIC by mistake. | |
| Dec 1, 2015 at 19:45 | comment | added | Majenko | @jwpat7 Surely you mean tri-state outputs, not open-drain outputs... | |
| Dec 1, 2015 at 18:28 | comment | added | James Waldby - jwpat7 | Jesse Mount, please edit question and specify voltages used; whether voltage translators/shifters are used; and the model numbers of the readers. While SPI slaves typically use open-drain outputs so MISO can be wired together, some don't. Without a model number, who can say? | |
| Dec 1, 2015 at 18:26 | comment | added | James Waldby - jwpat7 | @frarugi87, that the readers work individually suggests that's not the problem. Also, MISO is an input to Arduino and 3V3-system outputs to 5V-system inputs are said to work ok. | |
| Dec 1, 2015 at 15:31 | comment | added | frarugi87 | You are using a 5V arduino board without voltage translators, right? If so, you are out-of-specs for those modules, so this can make them malfunction | |
| Dec 1, 2015 at 14:55 | review | First posts | |||
| Dec 13, 2015 at 11:00 | |||||
| Dec 1, 2015 at 14:52 | history | asked | Jesse Mount | CC BY-SA 3.0 |
