1.1 Disconnection from Peer Device after Short Duration

Issue

The IS1677SM, which is the SiP IC used in BM77 and RN4677 modules, contains a Flash die from a third party. Since 2021, the IS1677SM devices have shipped containing a Flash die with slower read access time, which cannot meet timing requirements across all operating conditions. The symptoms of such a situation include:

  • After connecting to a peer Bluetooth® device and exchanging data over SPP, the module might disconnect after a few minutes of operation and require a power-cycle reset to recover.

Work Around

  1. Migrate to the IS1678 IC or BM78/RN4678 module. The BM78/RN4678 modules are Bluetooth Dual mode modules that are pin compatible with the BM77/RN4677 module. The IS1678/BM78/RN4678 devices have more advanced features than the IS1677SM/ BM77/RN4677 devices. Migration guides are available to assist with the transition and can be found on the product pages for the BM78 and RN4678 modules on the Microchip Website. The recommended BM78/RN4678 CPNs are provided in the following table.
    Original DeviceRecommended Replacement
    BM77SPP03MC2-0003AA, BM77SPP03MC2-0004AA, BM77SPP03MC2-0006AA, BM77SPP03MC2-0007AA, BM77SPP03MC2-0008AA, BM77SPP03MC2-0009AA, BM77SPP03MC2-000AAA, BM77SPP03MC2-000BAA, BM77SPP05MC2-0006AABM78SPP05MC2-0B06AA
    BM77SPPS3MC2-0006AA, BM77SPPS3MC2-0007AA, BM77SPPS3MC2-0008AA, BM77SPPS3MC2-000AAA, BM77SPPS5MC2-0004AABM78SPPS5MC2-0B06AA
    RN4677-V/RM100, RN4677-V/RM112RN4678-VB/RM122
  2. Software mitigation: Increase the internal voltage setting for the LDO18 parameter in the memory configuration for the BM77/RN4677 module. To implement this software mitigation, reach out to your Microchip representative or Microchip support.