FreeCalypso > hg > freecalypso-reveng
diff sim-card-detect @ 368:82d5cc869bf1
sim-card-detect observations note added
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Thu, 26 Nov 2020 04:45:20 +0000 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/sim-card-detect Thu Nov 26 04:45:20 2020 +0000 @@ -0,0 +1,21 @@ +On the Mother's D-Sample board the SIM card status register (FFFE:0002) +reads: + +0x000A (CD bit 0) when the SIM socket is empty +0x000B (CD bit 1) when a card is inserted and the switch is shorted + +These register readings match CAL207 register document. + +On FCDEV3B Calypso SIM_CD input is tied high following Leonardo and Openmoko, +and the register reads 0x000B - thus we reach the conclusion that CAL000 +document is correct in that logic high on SIM_CD is supposed to indicate SIM +inserted, whereas logic low is supposed to indicate an empty SIM socket. + +However, the netlist extracted from the PADS PCB file for E-Sample (Calypso+ +chipset) shows the opposite arrangement: it shows a pull-up resistor to V-IO on +the SIM-CD net, and the switch in the SIM socket shorts this net to ground. +Perhaps the sense of this signal is inverted on Calypso+? We have no way of +knowing because we have no documentation for Calypso+, but we do know that its +ABB companion Syren reversed the sense of its test reset signal (relative to +Iota) for no apparent reason, hence such signal polarity reversals are not out +of the question.