Change in simtrace2[master]: cardem: ensure VCC_PHONE is floating

[laforge]

Hello tsaitgaist,

I'd like you to do a code review. Please visit

    https://gerrit.osmocom.org/c/simtrace2/+/23621

to review the following change.


Change subject: cardem: ensure VCC_PHONE is floating
......................................................................

cardem: ensure VCC_PHONE is floating

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

XX pin reconfig

Change-Id: Ib261073e3779ae7d98de18ce78b34ff37eafeaa2
---
M firmware/libboard/simtrace/include/board.h
M firmware/libcommon/source/mode_cardemu.c
2 files changed, 17 insertions(+), 1 deletion(-)



  git pull ssh://gerrit.osmocom.org:29418/simtrace2 refs/changes/21/23621/1

diff --git a/firmware/libboard/simtrace/include/board.h b/firmware/libboard/simtrace/include/board.h
index 65e6197..bdc1eb7 100644
--- a/firmware/libboard/simtrace/include/board.h
+++ b/firmware/libboard/simtrace/include/board.h
@@ -120,6 +120,14 @@
 /* ISO7816-communication related pins */
 #define PINS_ISO7816            PIN_SIM_IO,  PIN_SIM_CLK,  PIN_ISO7816_RSTMC // SIM_PWEN_PIN, PIN_SIM_IO2, PIN_SIM_CLK2
 
+/** card emulation configuration */
+/* Disable power converter 4.5-6V to 3.3V (active high) */
+#define PIN_SIM_PWEN_CARDEMU   {PIO_PA5, PIOA, ID_PIOA, PIO_OUTPUT_0, PIO_DEFAULT}
+/* Disable power switch to forward VCC_PHONE to VCC_SIM (active high) */
+#define PIN_VCC_FWD_CARDEMU    {PIO_PA26, PIOA, ID_PIOA, PIO_OUTPUT_0, PIO_DEFAULT}
+/* Disable power to SIM */
+#define PINS_PWR_CARDEMU        PIN_SIM_PWEN_CARDEMU, PIN_VCC_FWD_CARDEMU
+
 /** External SPI flash interface   **/
 /* SPI MISO pin definition */
 #define PIN_SPI_MISO  {PIO_PA12A_MISO, PIOA, PIOA, PIO_PERIPH_A, PIO_PULLUP}
diff --git a/firmware/libcommon/source/mode_cardemu.c b/firmware/libcommon/source/mode_cardemu.c
index 32d3b17..50fe668 100644
--- a/firmware/libcommon/source/mode_cardemu.c
+++ b/firmware/libcommon/source/mode_cardemu.c
@@ -546,12 +546,20 @@
 
 	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);

-- 
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Gerrit-Project: simtrace2
Gerrit-Branch: master
Gerrit-Change-Id: Ib261073e3779ae7d98de18ce78b34ff37eafeaa2
Gerrit-Change-Number: 23621
Gerrit-PatchSet: 1
Gerrit-Owner: laforge <laforge at osmocom.org>
Gerrit-Reviewer: tsaitgaist <kredon at sysmocom.de>
Gerrit-MessageType: newchange
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