AFE7900EVM: Power Level Difference for NCO Frequency on AFE7900 (Latte vs Python)

Hi Bala,

In Latte are you using the python function, updateTxNco, or applying the direct register writes? Is the power before updating the NCO correct? Can you share the script you are using the configure the AFE?

I have tested using the exact same register writes for TxD and see no change in amplitude when using the direct register writes. 

Regards,

David Chaparro 

Hi David,

In latte, I am using the AFE.updateTxNco() function to update the NCO frequency. The power level was correct before updating the NCO frequency.

First time I have updated the NCO frequency to 2 GHz using latte(using AFE.updateTxNco()). the power level is -27.03 dBm.

Now I have restarted the AFE and this time I tried to update the NCO frequency(2 GHz) through python scripts in linux where the python script will take the SPI write file as argument. The power level here is -48.51 dBm. So I think the power level is not correct when updating through the python script.

I have attached the python script for generating the NCO SPI writes and the python script to update the NCO frequency.

"""
	@file	  NcoControllerCommandsGenerator.py
	@brief	  Generates NCO controller commands.
	@details  This python script is called by the frequency receiver server.
			  This gets a frequency and a filename as command line arguments.
			  This then generates NCO register values for Rx and Tx
			  configuration and writes to the specified file.
	
	@param	  [in] NCO_FREQUENCY The frequency for which Tx and Rx NCOs of 
			  AFE has to be configured.
	@param	  [in] OUTPUT_FILENAME The filename to which modified register
			  values have to be written.
"""

from sys import argv

F_ADC = 2949.12
F_DAC = 2949.12 * 4

TX_PAGE_ADDRESS = 0x19
TX_MIXER_BASE_ADDRESS = 0x350
TX_RESET_ADDRESS = 0x773

RX_PAGE_ADDRESS = 0x12
RX_MIXER_BASE_ADDRESS = 0xa0
RX_RESET_ADDRESS = 0x180

DATA_LENGTH_IN_BYTES = 4

COMMAND_FORMAT = "SPIWrite {:04x},{:02x},0,7"

CHANNELS = ['A', 'B', 'C', 'D']
DEFAULT_OPENED_RX_CHANNELS = 0x00	# By default no channels will be opened
DEFAULT_OPENED_TX_CHANNELS = 0x00	# By default no channels will be opened

def get_afe_config_commands(f_nco, channels_to_be_opened, options):
    """
        @brief    Main function that runs when this file is ran.
        @details  This function modifies some register values for configuring Tx
                  and Rx NCOs of AFE. Those values are got after some calculations
                  on the nco frequency received as command line argument. These 
                  outputs are then written to a file which is also got as second
                  command line argument.
        @return   Returns nothing.
    """
    
    F_NCO = f_nco
    
    ##################
    ##  For Rx NCO  ##
    ##################
    
    opened_rx_channels = DEFAULT_OPENED_RX_CHANNELS
    for channel in CHANNELS:
        if(channel in channels_to_be_opened):
            opened_rx_channels = opened_rx_channels | (0x01 << (ord(channel) - ord(CHANNELS[0])))
    
    F_NCO_RX = F_NCO
    
    # Bringing F_NCO_RX to a value less than or equal to F_ADC (only if F_NCO_RX is greater than F_ADC)
    if(F_NCO_RX > F_ADC):
        if(F_NCO_RX % F_ADC == 0):
            F_NCO_RX = F_ADC
        else:
            F_NCO_RX = F_NCO_RX % F_ADC
            
    #print("F_NCO_RX is %.1f"%(F_NCO_RX))
    
    FCW_DECIMAL = int(round((F_NCO_RX*2**32)/F_ADC))
    #print("FCW_DECIMAL is %d"%(FCW_DECIMAL))
    
    # Commands in the beginning of output file
    rx_commands_start = [
        COMMAND_FORMAT.format(RX_PAGE_ADDRESS, opened_rx_channels),    # Command to open RX channels
    ]
    
    # Commands in between of output file
    rx_commands_between = []
    
    # Commands at the end of output file
    rx_commands_end = [
        COMMAND_FORMAT.format(RX_RESET_ADDRESS, 0x00),    # Commands to reset opened RX channels
        COMMAND_FORMAT.format(RX_RESET_ADDRESS, 0x01),
        COMMAND_FORMAT.format(RX_RESET_ADDRESS, 0x00),
        COMMAND_FORMAT.format(RX_PAGE_ADDRESS, 0x00),    # Command to close opened RX channels
    ]
    
    address = RX_MIXER_BASE_ADDRESS
    
    for i in range(DATA_LENGTH_IN_BYTES):
        data = FCW_DECIMAL & 0xff    # Taking the last byte
        rx_commands_between.append(COMMAND_FORMAT.format(address, data))
        FCW_DECIMAL = FCW_DECIMAL >> 8    # Removing the last byte
        address = address + 1
    
    rx_commands = rx_commands_start + rx_commands_between[::-1] + rx_commands_end
    
    ##################
    ##  For Tx NCO  ##
    ##################
    
    opened_tx_channels = DEFAULT_OPENED_TX_CHANNELS
    for channel in CHANNELS:
        if(channel in channels_to_be_opened):
            opened_tx_channels = opened_tx_channels | (0x10 << (ord(channel) - ord(CHANNELS[0])))
    #print(opened_tx_channels)
    F_NCO_TX = F_NCO
    
    # Bringing F_NCO_TX to a value less than or equal to F_DAC (only if F_NCO_TX is greater than F_DAC)
    if(F_NCO_TX > F_DAC):
        if(F_NCO_TX % F_DAC == 0):
            F_NCO_TX = F_DAC
        else:
            F_NCO_TX = F_NCO_TX % F_DAC
    
    FCW_DECIMAL = int(round((F_NCO_TX*2**32)/F_DAC))
    
    # Commands in the beginning of output file
    tx_commands_start = [
        COMMAND_FORMAT.format(TX_PAGE_ADDRESS, opened_tx_channels),    # Command to open 4 TX channels
    ]
    
    # Commands in between of output file
    tx_commands_between = []
    
    # Commands at the end of output file
    tx_commands_end = [
        COMMAND_FORMAT.format(TX_RESET_ADDRESS, 0x00),    # Commands to reset opened TX channels
        COMMAND_FORMAT.format(TX_RESET_ADDRESS, 0x01),
        COMMAND_FORMAT.format(TX_RESET_ADDRESS, 0x00),
        COMMAND_FORMAT.format(TX_PAGE_ADDRESS, 0x00),    # Command to close opened TX channels
    ]
    
    address = TX_MIXER_BASE_ADDRESS
    
    for i in range(DATA_LENGTH_IN_BYTES):
        data = FCW_DECIMAL & 0xff    # Taking the last byte
        tx_commands_between.append("SPIWrite %04x,%02x,0,7"%(address, data))
        FCW_DECIMAL = FCW_DECIMAL >> 8    # Removing the last byte
        address = address + 1
    
    tx_commands = tx_commands_start + tx_commands_between[::-1] + tx_commands_end
    
    commands = []
    
    if("--skip-rx" not in options):
        commands.extend(rx_commands)
    else:
        print("Skipping rx commands...")
    
    if("--skip-tx" not in options):
        commands.extend(tx_commands)
    else:
        print("Skipping tx commands...")
    
    return commands

if __name__ == "__main__":
    if(len(argv) < 7):
        print("Usage: python NcoControllerCommandsGenerator.py --c -hannels [CHANNEL_NAMES_SEPARATED_WITH_COMMA] --fnco [NCO_FREQUENCY] --of [OUTPUT_FILENAME] [OPTIONS]")
        print("Options: ")
        print("--skip-rx\t-\tTo skip commands for rx channels")
        print("--skip-tx\t-\tTo skip commands for tx channels")
        exit(-1)
    
    channels_to_be_opened = [channel.upper() for channel in argv[argv.index("--channels") + 1].split(",")]
    f_nco = float(argv[argv.index("--fnco") + 1])
    output_filename = argv[argv.index("--of") + 1]
    
    commands = get_afe_config_commands(f_nco, channels_to_be_opened, argv)
    
    with open(output_filename, "w") as file:
        file.write("\n".join(commands))
    
    print("A new file %s has been created with register values for frequency %.1f"%(output_filename, f_nco))

#!/bin/python
from sys import argv, stdout
from time import sleep
from pyftdi.spi import SpiController

SCHEME = "ftdi"
VENDOR_ID = 0x0403
PRODUCT_ID = 0x6011
INTERFACE = 1

SPI_WRITE = "SPIWrite"
SPI_READ = "SPIRead"
SPI_READ_CHECK = "SPIReadCheck"
SPI_POLL = "SPIPoll"
WAIT = "WAIT"

SPI_POLL_MAX_COUNT = 100

URL_FMT = "{scheme}://{vendor_id}:{product_id}/{interface}"
URL = URL_FMT.format(scheme=SCHEME, vendor_id=VENDOR_ID, product_id=PRODUCT_ID, interface=INTERFACE)

def get_afe_spi_handle():
    spi_controller = SpiController()
    spi_controller.configure(url=URL)
    afe_spi_handle = spi_controller.get_port(cs=0, freq=12E6, mode=0)
    
    return afe_spi_handle

def program_afe(afe_spi_handle, spi_commands):
    ## Iterating through each line of commands
    for spi_command in spi_commands:
        
        ## Stripping the string
        spi_command = spi_command.strip()
        
        ## Skip the line if empty
        if(not spi_command):
            continue
        
        if(spi_command.startswith(SPI_WRITE)):
            spi_command_split = spi_command.split()[1].split(",")
            spi_command_bytes = bytes([int(spi_command_split[0][:2], 16), int(spi_command_split[0][2:4], 16), int(spi_command_split[1], 16)])
            afe_spi_handle.write(spi_command_bytes)
            response_bytes = afe_spi_handle.read(1)
            print("[{}] Addr: {:04x} Data: {:02x}".format(SPI_WRITE, spi_command_bytes[0] << 8 | spi_command_bytes[1], spi_command_bytes[2]))
        elif(spi_command.startswith(SPI_READ_CHECK)):
            spi_command_split = spi_command.split()[1].split(",")
            spi_command_bytes = bytes([int(spi_command_split[0][:2], 16) | 1 << 7, int(spi_command_split[0][2:4], 16), int(spi_command_split[3], 16)])
            afe_spi_handle.write(spi_command_bytes[:2])
            response_bytes = afe_spi_handle.read(1)
            print("[{}] Addr: {:04x} Exp: {:02x} Read: {:02x}".format(SPI_READ_CHECK, (spi_command_bytes[0] & ~(1 << 7)) << 8 | spi_command_bytes[1], spi_command_bytes[2], response_bytes[0]))
        elif(spi_command.startswith(SPI_READ)):
            spi_command_split = spi_command.split()[1].split(",")
            spi_command_bytes = bytes([int(spi_command_split[0][:2], 16) | 1 << 7, int(spi_command_split[0][2:4], 16)])
            afe_spi_handle.write(spi_command_bytes)
            response_bytes = afe_spi_handle.read(1)
            print("[{}] Addr: {:04x} Read: {:02x}".format(SPI_READ, (spi_command_bytes[0] & ~(1 << 7)) << 8 | spi_command_bytes[1], response_bytes[0]))
        elif(spi_command.startswith(SPI_POLL)):
            spi_poll_count = SPI_POLL_MAX_COUNT
            spi_command_split = spi_command.split()[1].split(",")
            spi_command_bytes = bytes([int(spi_command_split[0][:2], 16) | 1 << 7, int(spi_command_split[0][2:4], 16), int(spi_command_split[3], 16)])
            response_bytes = None
            print("[{}] Addr: {:04x} Exp: {:02x}".format(SPI_POLL, (spi_command_bytes[0] & ~(1 << 7)) << 8 | spi_command_bytes[1], spi_command_bytes[2]))
            while(spi_poll_count > 0):
                afe_spi_handle.write(spi_command_bytes[:2])
                response_bytes = afe_spi_handle.read(1)
                if(response_bytes[0] == spi_command_bytes[2]):
                    break
                spi_poll_count = spi_poll_count - 1
            if(spi_poll_count == 0):
                print("[{}] Failed".format(SPI_POLL))
            else:
                print("[{}] Success".format(SPI_POLL))
        elif(spi_command.startswith(WAIT)):
            sleep_time_s = float(spi_command.split()[1])
            print("[{}] {}".format(WAIT, sleep_time_s))
            sleep(sleep_time_s)
        else:
            pass

if(__name__ == "__main__"):
    if(len(argv) < 2):
        print("Usage: python3 programAFE.py [LOG FILE]")
        exit(1)
    
    log_file_name = argv[1]
    
    try:
        log_file = open(log_file_name, "r")
        spi_commands = log_file.readlines()
        log_file.close()
        
        afe_spi_handle = get_afe_spi_handle()
        program_afe(afe_spi_handle, spi_commands)
    except FileNotFoundError:
        print("Error: Could not find file \"{}\"".format(log_file_name))
        exit(1)

Regards,

Bala

Hi David,

I have tried again setting the NCO frequency through python code. On further testing, I found that the NCO frequency for RX is being set but the NCO frequency for TX is not while using the python code. So please check this on your side and give me a update regarding this.

Regards,

Bala

Hi Bala,

One thing that could cause an issue like this is the SPI writes not closing the appropriate pages. Can you share the register sequence you use to program the AFE before running the update NCO writes? 

Regards,

David Chaparro 

Hi David,

I have attached the register sequence to program AFE. 

Regards,AFECommands.txt

Bala