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SPI communication of PGA 450-Q1 with another Microcontroller

Alibert Lionel
Prodigy 40 points
Other Parts Discussed in Thread: PGA450-Q1, TIDA-00151, MAX3221, PGA450Q1EVM
Hello,
 
To explain my project: I want to establish a SPI communication between the PGA450-Q1 and a Cypress PGA processor to create my own HMI.
My problem is that I do not find the address and the read/write commands for the register that will allow me to recover the data from the PGA so that I can structure my code correctly.
My question is this: is this feasible or not with the SPI since I want to replace the 8051 processor that is connected to the PGA with a Cypress microcontroller? if that is the case I would like to find the good values for the commands and register addresses !!  However, if this is not possible, do I have another alternative?
Thank you
 
Regards,


thank you

  • 0
    TI__Mastermind 27780 points
    Alibert,
    Allow me to make you aware of the PGA450-Q1 SPI limitations:
    • SPI is only intended to be used for development and debug purposes. Use LIN or SCI for the final product's digital communication.
    • The PGA450-Q1 internal 8051W only acts as an SPI-slave device.
    • The PGA450-Q1 does not respond to SPI messages unless the 8051W microprocessor is in the reset state.

    During the reset state, SPI is the only digital interface that can be used. The low-side drivers can still be triggered to begin an ultrasonic burst and the analog front-end and digital data path can still store the returned echo signal in the FIFO RAM. However, any processing of the FIFO RAM by the internal microprocessor to determine the location of an object does not occur. The FIFO RAM data can be read over SPI, allowing an external microprocessor to process the data.

    Make sure you are using Rev.B of the PGA450-Q1 datasheet which contains the Programmer's Guide listing all user accessible register addresses and bit definitions. (Rev.B was recently uploaded to the product page last month.)

    I recently answered a similar post on how to use SPI via an example. The example should note that the MICRO is assumed to be in the RESET state. See the post here: e2e.ti.com/support/applications/automotive/f/26/p/226046/1560522#1560522
  • 0 in reply to Akeem Whitehead
    Prodigy 40 points
    Hello,
    At the moment I want to control the PGA with a Cypress processor. What I would like to do is to establish communication between the two by writing data and then reading it while being completely independent from the 8051 processor. If this is not feasible with SPI ,  could I do it with UART?
     
    Best regards,
  • 0 in reply to Alibert Lionel
    TI__Mastermind 27780 points
    Alibert,
    We recommend you use UART to communicate between the PGA450-Q1 and Cypress processor instead of SPI. Please refer to the the "TIDA-00151 UART Instructional" (www.ti.com/.../slva718) and supporting "TIDA-00151 UART Demo Firmware for PGA450-Q1" (www.ti.com/.../tidcab3) that demonstrates this method.
  • 0 in reply to Akeem Whitehead
    Prodigy 40 points
    Hello,
    I tried to refer to the datasheet you sent me (tida instructional UART) and establish a communication between Cypress and the PGA450 using the pins of the TigerBoard at the beginning and then with the pins of the U2 but unfortunately communication is not achieved between the two cards.
    On the contrary, communication is possible if I use the rx and tx pins of the RS232 Port (U4).
    The questions I ask myself and need clarifications on are:
    Could I initialize the PGA and send commands at the same time to retrieve data from the RS232 port? If this is the case, how is it done?
    If this is not the case, can you point me to the settings I need to check regarding the replacement of the TigerBoard? Since I have tried to connect to the pins of the Tiger with the Cypress processor but communication was not possible, I even tried to connect the pins of the U2 with a cable (txd and rxd) and I have the same problem !!

    Regards,
  • 0 in reply to Alibert Lionel
    TI__Mastermind 27780 points
    Alibert,
    Please note that the TIDA-00151 UART Instructional is based on the hardware configuration of the reference design. The instructional does not account for the RS232 transceiver circuitry present on the PGA450Q1EVM. Unfortunately, the PGA450Q1EVM does not provide a jumper option to bypass the MAX3221 transceiver, so you cannot connect the TIGER UART pins directly to the PGA450-Q1's Tx and Rx pins without isolating these pins from the transceiver circuit. The transceiver circuit is likely interfering with the expected operation of the TIGER to PGA450-Q1 communication when sharing the UART bus.

    The objective of the RS-232 port is to allow you to continue using UART if you have an RS232-to-USB cable to connect to your PC for instance. As you have already figured out, you can access the transceiver's Rx and Tx pins of the RS232 (U4) port to bypass the need for the hardware cable adapter, and send/receive commands just as you would when referencing the Instructional.

    I modified the EVM to isolate the PGA450-Q1 TX and RX pins, and confirmed that the UART Instructional applies and works with the TIGER board and PGA450Q1EVM. This modification could be to either desolder the transceiver circuit block, or cut the traces from the transceiver block to the PGA450-Q1's Rx/Tx pins.

    I understand that you ultimately will remove the TIGER from the system, and only connect the PGA450-Q1 to the Cypress processor, correct? The TIGER board is only being used for your initial evaluation, correct? Ensure that your Cypress processor is using the same UART configuration settings as the TIGER (refer to "UART CONTROL SETTINGS" of TIGER GUI in UART Instructional document).