Quite sure it's a hardware bug, going to replace the chips 21-4-2015... We've got two 'identical' set-ups with the same code on it... but they both act different... (None works)
I'm currently working on a project involving a TRF7970A (SPI), so far I have managed to set up the SPI connection and read/write the registers. But I seem unable to create a RF field.
- Project: RFID Reader
- MCU: PIC18F66K22
- Reader: TRF7970A
- Problem: No RF field
- Working: SPI connection (Reading/Writing registers)
It's quite hard to find any projects with this reader, which are clear on what to set the registers to and I'm hoping if anyone has experience with the TRF7970A.
The register values I set / think are needed are:
Chip Status Control Register (0x00) Bit 5 = 1 (RF output active) Bit 0 = ? (3V or 5V operation, tried both, could this damage the chip?) (I'm working with PIC (~3,3V) but source is LI-ION ~3,7V) (This is compliant with an earlier project, in which it did work)
Regulator and I/O Control Register 0x0B Tried Bit 7 = 1 (Auto-regulation) Aswel as manual settings
I just see that in 3V mode VDD_RF goes from 2,7V to 3,4V and in 5V mode it goes from 4,3V to 5V. Is it possible that in 3,7V (LI-ION/Working voltage) The TRF7970A will not work?
For this moment, the ISO settings/ protocol etc don't really matter, I just want to get an RF field (measured with oscilloscope). So powering it with a Li-Ion (3,7V) is wrong? Or what register settings am I missing? The osccilator of the chip seems to be working fine.