Digital TTL I/O
6.4
Note that some digital inputs are internally used in the other parts of the TPMC851:
TTL I/O line 0 as ADC sequencer trigger
TTL I/O line 1 as DAC sequencer trigger
TTL I/O line 2 and TTL I/O line 3 as counter inputs
TTL I/O line 4 as counter control input
Normally the usage of these digital I/O lines is not subject to any restrictions, as long as they are used as inputs
(i.e. as trigger for a sequencer). Exceptions are I/O lines 0 and 1, these can also be used as sequencer trigger
output.
If ADC_OUT in the Line Direction Register LINEDIR is set to ‘1’, the trigger signal for the ADC sequencer is
available for external use on Dig I/O Line 0.
If DAC_OUT in the Line Direction Register LINEDIR is set to ‘1’, the trigger signal for the DAC sequencer is
available for external use on Dig I/O Line 1.
In this case the settings in the Line Direction Register for these I/O lines (LINEDIR0 resp. LINEDIR1) are
overridden and they are always used as output. Writes in the Line Output Register to these I/O lines (LINEOUT0
resp. LINEOUT1) have no effect.
Avoid to use this configuration while the sequencer is set to wait for an external trigger (ADC: SEQ_TRIG
= 1; DAC: LOAD_SEL = 11). This will cause the sequencer to lock.
If it is required to use the I/O line as sequencer trigger input and output at the same time, this can be achieved
with following solution:
o
Configure the sequencer to wait for an external trigger (ADC: SEQ_TRIG = 1; DAC: LOAD_SEL = 11)
o
Configure the I/O Line as output (ADC: LINEDIR0 = 1; DAC: LINEDIR1 = 1)
o
Trigger the sequencer with a write to the Line Output Register (ADC: LINEOUT0 = 1; DAC: LINEOUT1 = 1)
TPMC851 User Manual Issue 1.0.9
Page 56 of 65
