Sharp Blue Treak LH75400 User Manual

Analog-to-Digital Converter/Brownout Detector LH75400/01/10/11 (Preliminary) User’s Guide23-16 6/25/0323.3.2.6 General Configuration RegisterGC is the General Configuration Register. The active bits used in this register areRead/Write.In this register, the SSM signal triggers the state machine to retrieve the data from the con-trol bank and store it in the appropriate registers for the ADC. If the SSM bit is set to 11 atthe end of a sequence, the state machine continues to convert data.If the SSM bits are set to 10 and a value of 0b0000110 is written to the GC Register, theEOSINTR_UM bit (bit [2]) of the Interrupt Status Register may never get set. This is normaloperation. To accommodate this, wait two A2DCLK periods after setting the SSM bit to 10before setting the SSB bit.NOTE: Allow two A2DCLK cycles between successive write cycles to this register. Otherwise, ADC behaviorcan become erratic.Table 23-14. GC RegisterBIT 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16FIELD ///RESET 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0RW R R R R R R R R R R R R R R R RBIT 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0FIELD /// FIFOWMK SSB SSMRESET 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0RW R R R R R R R R R RW RW RW RW RW RW RWADDR 0xFFFC3000 + 0x14Table 23-15. GC Register DefinitionsBIT NAME DESCRIPTION31:7 /// Reserved Read as zero.6:3 FIFOWMKFIFO Watermark Programmed to values between 0 and 15. This value cor-responds to watermark levels between 1 and 16, respectively. When the FIFOfills to this level, the FIFO generates an interrupt.2 SSBStart Sequence Bit0 = SSB will not start conversion sequence.1 = SSB will start conversion sequence.1:0 SSMSequence Start Mode00 = SSB or Pen Interrupt starts new conversions.01 = Pen Interrupt starts new conversions.10 = SSB starts new conversions.11 = Continuous conversions.To trigger continuous conversions, set these bits to ‘11’, wait one A2DCLKperiod, and set the SSB bit to ‘1’. Thereafter, once any conversions occur andSSM is set to ‘00’ to stop the conversions, conversions can be started againby setting SSM to ‘11’, without having to set SSB. Note that the Pen Interruptcan only be used when the ADC is configured to start on Pen Down. For moreinformation, see Section 23.3.2.7.