Datasheet

971
SAM9X35 [DATASHEET]
11055E–ATARM–10-Mar-2014
42.8.22 ADC Trigger Register
Name: ADC_TRGR
Address: 0xF804C0C0
Access: Read-write
• TRGMOD: Trigger Mode
• TRGPER: Trigger Period
Effective only if TRGMOD defines a Periodic Trigger.
Defines the periodic trigger period, with the following equation:
Trigger Period = (TRGPER+1) /ADCCLK
The minimum time between 2 consecutive trigger events must be strictly greater than the duration time of the longest conversion
sequence according to configuration of registers ADC_MR, ADC_CHSR, ADC_SEQR1, ADC_SEQR2, ADC_TSMR.
When TRGMOD is set to pen detect trigger (i.e. 100) and averaging is used (i.e. bitfield TSAV differs from 0 in ADC_TSMR regis-
ter) only 1 measure is performed. Thus, XRDY, YRDY, PRDY, DRDY will not rise on pen contact trigger. To achieve
measurement, several triggers must be provided either by software or by setting the TRGMOD on continuous trigger (i.e. 110)
until flags rise.
31 30 29 28 27 26 25 24
TRGPER
23 22 21 20 19 18 17 16
TRGPER
15 14 13 12 11 10 9 8
––––––––
76543210
–––––
TRGMOD
Value Name Description
0 NO_TRIGGER No trigger, only software trigger can start conversions
1 EXT_TRIG_RISE External Trigger Rising Edge
2 EXT_TRIG_FALL External Trigger Falling Edge
3EXT_TRIG_ANYExternal Trigger Any Edge
4 PEN_TRIG
Pen Detect Trigger (shall be selected only if PENDET is set and TSAMOD = Touchscreen
only mode)
5 PERIOD_TRIG Periodic Trigger (TRGPER shall be initiated appropriately)
6 CONTINUOUS Continuous Mode
7–Reserved