LVDT Measurement (Module L*)68C3 Operations Manual North Atlantic Industries, Inc. 12/19/2014Rev: 2014-12-19-0947 www.naii.com Page 218 of 330Buffer Data Type:Different types of data format can be stored in the FIFO buffer and their formats are defined by the Buffer ControlRegister. The following bit mask defines the type/format of data that will be put into the FIFO buffer.B0 = Data (16-bit Hi). 16-bit resolution data.B1 = Data (8-bit Lo). Combine with B0 to form a 24-bit resolution.B2 = Filtered Data (16-bit Hi). Filtered 16-bit resolution data.B3 = Filtered Data (8-bit Lo). Combine with B2 to form filtered 24-bit resolution.B4 = Time Stamp. An integer counter that counts from 0 to 65,535 and wraps around when it overflows.B5 = ReservedB6 = ReservedB7 = ReservedNote: Each data format (B0 – B4) requires one word of storage space from the FIFO buffer. For example, if B0, B1 and B4are set (0x13) and the Size register is set to 1, a FIFO write will put 3 words of data to the FIFO memory spaces. Since themaximum physical size of FIFO is 65,535 for each channel, the value in the Size and Buffer Control register could cause anoverflow to the FIFO buffer. When an overflow condition occurs, any un-stored data will be lost.Description Buffer Ctrl.(16-bit hex)Buf. Ctrl. in ch1-4 Data Range: b0-b4Trigger Mode:The FIFO can be started/triggered by different sources.B0-B1 = Source Select (choose one only)0x0 = Ext. Trigger 20x1 = Ext. Trigger 10x2 = Software TriggerB3 = ReservedB4-B7 = Trigger Type (Choose one only)0x10 = Negative Slope0x20 = Trigger Pulse Enable0x40 = Trigger Pulse/Trigger Enable Select0x80 = Trigger ClearDescription Trigger Ctrl.(16-bit hex)Trigger Ctrl. in ch1-4 Data Range: B0-B7Software Trigger:Software trigger is used to kick start the FIFO buffer and the collection of data. In order to use this operation, the“Trigger Ctrl” register must be set up properly. Setting or resetting the “Software Trigger” will start FIFO datacollection for ALL channels.Description Software Trigger (16-bit hex)Software Trigger Data Range: 0x0-0xFFFFRegisterWrite Trig Source Slope0x20 Ext Trigger 2 Positive0x21 Ext Trigger 1 Positive0x22 SW Trigger Positive (don’t care)0x30 Ext Trigger 2 Negative0x31 Ext Trigger 1 Negative0x32 SW Trigger Negative (don’t care)0x40 Initiate0x80 Stop (Clear Trigger)16Bit Hi8Bit LoTimeStamp
