After the CYW20736/20737-based kit is reset or power-cycled (switched OFF, then ON), the application does not run. Why?
This is expected because kits such as BCM92073X_LE_TAG4 or CYBLE-013025-EVAL set HCI_RX to ‘high’ when the HCI UART_RX connects to the USB-to-UART device. The CYW20736/20737 boot code will set the device to download mode if the HCI_RX is high after reset or after being power-cycled. To run the application code, set the HCI_RX switch to OFF. For example, set SW4-2 to OFF and then reset the device to run the application mode with BCM920737TAG-03.
How do you download the application hex to run the CYW20736/20737-based kit successfully?
- Recover the kit using hardware by following this sequence: Power the kit > Press the Recover button > Press the Reset button > Hold for one second > Release the Reset button > Release the Recover button. Now, download the application hex again.
- If this does not work, make sure that the HCI UART switch is set to ON. Find the HCI_UART port in the PC’s system manager; if your kit (for example, BCM92073X_LE_TAG4) has two UART ports, the smaller one is the HCI UART and the larger one is Puart. If the kit has only one UART port, then that port is the HCI UART; set only the HCI UART switch to ON. Enter ‘UART=COMXXX’ in the Make target field, where XXX is the HCI UART port number. For example, “hello_sensorBCM920737TAG_Q32 UART=COM1 download”. Download the application hex again.
- If programing fails after step 2, verify the kit’s NV-RAM type. The default NV-RAM is EEPROM. If the kit uses Sflash, enter ‘PLATFORM_NV=SFLASH’ in Make target field. For example, “hello_senso-BCM920737TAG_Q32 download UART=COM1 PLATFORM_NV=SFLASH”. Download the application hex again.
- If step 3 also does not work, use “recover” instead of “download” in the Make target field. For example,”hello_sensorBCM920737TAG_Q32 recover UART=COM1 PLATFORM_NV=SFLASH”.