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cardem: ensure VCC_PHONE is floating

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this change is mainly relevant for the SIMtrace board, but also
affects the others.
First we ensure VCC_PHONE is not forwarded to VCC_SIM because the
card could affect the signal (card could draw too much current or
feed back current in).
next we disable VCC_SIM. the card slot does not need to be
powered, and the FPF2019 leaks current back to VCC_PHONE, even
with forwarding disabled (the reverse current protection only
kicks in when VCC_PHONE is briefly shorted to ground, but still
leaks 0.6V).
enable the ADC channels normally used to measure VCC, even if
not used. the dedicated ADC pins leak current when left
unconfigured. enabling them puts them in high impedance.

Change-Id: If1487c1c191838aaa08b654e49cd31c7180ffc19
This commit is contained in:
Kévin Redon
2019-07-18 18:50:51 +02:00
parent 76c2eebae2
commit 90abc09cf3
2 changed files with 17 additions and 1 deletions
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10
firmware/libcommon/source/mode_cardemu.c
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@@ -508,12 +508,20 @@ void mode_cardemu_init(void)
TRACE_ENTRY();
#ifdef PINS_PWR_CARDEMU
// enable power on required peripherals, else disable
Pin pins_pwr_cardemu[] = { PINS_PWR_CARDEMU };
PIO_Configure(pins_pwr_cardemu, PIO_LISTSIZE(pins_pwr_cardemu));
#endif /* PINS_PWR_CARDEMU */
#ifdef PINS_CARDSIM
PIO_Configure(pins_cardsim, PIO_LISTSIZE(pins_cardsim));
#endif
// ADC channel 6 and 7 are used to measure VCC (else they are grounded)
ADC->ADC_CHER |= ADC_CHER_CH6 | ADC_CHER_CH7; // enable the ADC channels to put them in high impedance (else they leak current)
#ifdef DETECT_VCC_BY_ADC
card_vcc_adc_init();
card_vcc_adc_init(); // configure the ADC to measure VCC
#endif /* DETECT_VCC_BY_ADC */
// TODO pull SIMtrace board SIM lines low, else they can leak current back to VCC
INIT_LLIST_HEAD(&cardem_inst[0].usb_out_queue);
rbuf_reset(&cardem_inst[0].rb);