TDC1000-C2000EVM: Short circuiting 0 ohm resistor between TX1 and RX2 of TDC1000.

ns murthy,

Yes, you can short TX1 and RX2 to each other to enable a mono-static mode of operation to burst-and-listen using the same transducer. With this hardware configuration, you will need to ensure TOF_MEAS_MODE=0, so that CH_SEL=0 (channel 1) makes TX1 active and RX2 active.

Note: we have released a new family of ultrasonic devices supporting up to 1MHz transducer operation: the TUSS4440 and TUSS4470, which are intended to displace the TDC1000 due to improved performance and integrated features. We recommend using these TUSS44x0 devices instead of the TDC1000 moving forward.

ns murthy,

Responding to your questions:

1) The TDC72xx series is the only IC dedicated for time-to-digital conversion, but you can also use a simple low-end microcontroller with a single timer as an alternative. The TDC72xx can support pico-second resolution (mainly for LiDAR), which is excessive for most ultrasonic applications. Depending on the step resolution you require, micro-second resolution tends to be sufficient for ultrasonic time of flight capture. Note: the TUSS44x0 combines that start and stop pulses on a single pin (O3), so you only need to allocate one pin and one timer on your master controller to capture and convert the time-to-digital.

2) The TUSS44x0 is available for mass production now.

n s murthy,

The TUSS44x0 series is a general purpose ultrasonic driver and front end, so yes, you can use it for both water flow and level measurements. You can use the echo interrupt feature of pin O4 on the TUSS44x0 to get a similar digital toggle effect of the TDC1000's start and stop pulses to capture the time-of-flight using an MCU timer input or the TDC7200 device.

The TUSS44x0 devices are single channel devices, so you only need one for level measurements, but will need to use two TUSS44x0 devices in a flow measurement system (for up and down stream) measurements. Alternatively, you can use one TUSS44x0, and multiplex the transducer pairs to alternate transmit and receive direction for up and down stream measurements.

Given the TUSS44x0 are new, we are still working on content and applications notes for applications such as water flow and level sensing.

n s murthy,

I suspect it should be possible to use the TUSS44x0 devices with the TDC7200. The difference is that the TUSS44x0 combines the START and STOP pin functionality of the TDC1000 onto a single pin called O4 (output 4 for echo interrupt). Because of this, the TUSS44x0's O4 pin should be routed to both the START and STOP pins of the TDC7200. Technically, the first STOP (TIME1) will be the same as the START, so you'll always need to configure the TDC7200 to store at least two STOP captures to get the first real STOP at TIME2.

Be advised: This is implementation is all conceptual, and has not yet been validated. We eventually plan to test and create reference circuit material for the TUSS44x0 + TDC7200 to confirm this use-case. For your test purposes, please consider the TUSS4470 device specifically to support to 1MHz operation.