Sundance SMT148 User Manual
Page 29
Version 1.4
Page 29 of 35
SMT148 User Manual
ADC
The ADC interface is an input as well as an output node to the switch fabric. All eight
channels are controlled by this interface. It needs to receive settings before it can
transmit digitized samples to the interface it was initialized by.
To initialize a transfer or disconnect itself from the input node the ADC interface
expects to receive the following 32-bit word (4 consecutive bytes, LSB first):
Bit 31: new transfer initialization if 1.
Bit 30: disconnect from input node if 1, will result in a DONE pulse sent to the switch
fabric.
Bit 23 down to 16: output node address to which the digitized samples will be sent to
Bit 7 down to 0: Channels enable, 1 on bit X indicates that channel X will acquire
data, 0 that it will not.
After the ADC interface has been initialized it will start transmitting the digitized
samples through the switch fabric to the specified output node.
The first 32-bit word sent from the ADC interface to the switch fabric will address the
output node it needs to access.
Bit 31 down to 8: set to 0
Bit 7 down to 0: output node address (see table 14)
The next words sent to the switch fabric will have the following format:
Bit 31 down to 24: time stamp. This value is incremented by one every time a new
sample is available on a specific channel. If the receiver detects that 2 samples from
the same channel received consecutively have a time stamp difference not equal to
one, this means that some samples have been lost during transfer.
Bit 23 down to 16: channel to which the sample belongs, 1 on bit X indicates that the
sample belongs to channel X-16. All the other bits will be set to 0.
Bit 13 down to 0 : digitized sample value.
The ADC interface communicates with the ADC device on board using the following
nRD
Output
Read, active low
nCS
Output
Chip select, active low
nCONVST
Output
Convert start analog input, active low
CLKIN Output Conversion
Clock
BUSY
Input
Conversion is in progress
nSTBY
Output
Standby, active low
DATA_in
Input
14-bit data bus
Table 21 : ADC interface extra IO