PGA460-Q1： About the Test pin

user5127206,

Please clarify the following:

1) Are you able to successfully communicate to the PGA460 through UART?
If not, what data are you transmitting from the master to the PGA460? Example commands are listed in the PGA460 datasheet in section "7.5.1 UART and USART Communication Examples".

2) At what logic level is your master operating (3.3 or 5V)? By the default, the PGA460 operates at 3.3V logic levels. If you need to use 5V, then a 100kOhm pull-up resistor to 3.3 or 5V must be placed on the TEST pin.

3) Are you using the PGA460 in a test mode? By default, the TEST pin should always be a value of 0V. If you are using a test mode, then the value may not be 0V. The various test modes are listed in the PGA460 datasheet Table 5 in section "7.3.12 TEST Pin Functionality". Ensure the value of the TEST_MUX register is 0x00 (default).

4) Do you have a PGA460-Q1 EVM to verify UART communication to your external PGA460 module? It is possible to connect an external sensor module to the PGA460-Q1 EVM to evaluate custom hardware through the logic level USART mode, or the battery-logic one-wire interface (IO) mode in One-Wire UART or TCI mode. The PGA460 FAQ ( www.ti.com/.../slaa733.pdf ) #5.5 discusses how to connect an external module to the EVM for UART/USART mode. For an efficient flow of the setting configuration, refer to the PGA460 Ultrasonic Module Hardware and Software Optimization appnote.

Hi Akeem：

1)Now I can not communicate with the PGA460 through the Uart, the data I send is first sync byte 0x55, followed by the command byte, then the data, and finally the CRC check code!

2)My host uses a 5V logic level. I connect a 5V supply to the TEST pin and a 100K ohm pull-up resistor on the TEST pin. The voltage on the pull-up resistor is 4.98V and 1.49V respectively.

3)Now I use their own development of the circuit board can not communicate with the PGA460-Q1 EVM, now my own MCU to send a response command, PGA460 did not respond, what is the reason?

Hi user5127206,

For a 5V logic level connection, you have correctly setup the pull-up resistor on the TEST pin.

4) Can you provide a real example of your master's transmit sequence. Here are working examples from PGA460 datasheet section "7.5.1 UART and USART Communication Examples":
•Example1 – Read register 0x1B, where PGA460-Q1 address is 0x0:
Master to PGA460-Q1: 0x55, 0x09, 0x1B, 0xDB …
PGA460-Q1 to master: … 0xdiag, 0xdata, 0xchecksum
•Example2 – Write register 0x40, data 0x80, where PGA460-Q1 address is 0x0:
Master to PGA460-Q1: 0x55, 0x0A, 0x40, 0x80, 0x35
PGA460-Q1 to master:No response, idle (0xFF)

5) Be sure your master MCU is using the PGA460 required UART frame structure:
•8 data bits
•1 start bit
•2 stop bit
•No parity bit
•No flow control
•Interfield wait time (only required when using 1 stop bit)
Note: Most MCU's default to 1 stop bit, so ensure you have configured your master's UART port for 2 stop bits.

6)The PGA460 supports a baud rate between 2.4k-115.2kBaud. What baud rate are you using?

7) What is the value of VPWR? The PGA460 requires 6-28V to operate correctly. A 5V USB based supply will not be sufficient enough to power the PGA460.

8) For additional async UART examples, or to compute the checksum of any command sequence, refer to the GUI's Interface Mode --> UART page's command selection. Select the desired command from the drop-down with the appropriate UART Addr (0 by default), then click Run Command to see the raw serial sequence with appended checksum printed in Hex format on the UART terminal. You do not need to have the EVM connected in to use this feature of the GUI.

The PGA460 should return three values when using this command:
•Diagnostic field (0x40) if master transmit was successful
•Register address value
•PGA460 generated checksum

The threshold must be written to at least once after start-up to clear the threshold CRC error that is always flagged high on initialization. The threshold CRC error must be cleared before the PGA460-Q1 is allowed to execute a Burst & Listen or Listen-Only command.