NuMicro® NUC029LEE/NUC029SEE32-bit Arm® Cortex® -M0 MicrocontrollerAug, 2018 Page 358 of 497 Rev 1.00NUMICRO® NUC029LEE/NUC029SEE TECHNICAL REFERENCE MANUALSetting LEV_RTS(UA_MCR[9]) can control RTS pin output driving level. User can read theRTS_ST(UA_MCR[13]) bit to get real RTS pin output voltage logic status.LEV_RTS = 0LEV_RTS = 1RTS pin output status of RS-485 function mode (RS-485 AUD mode enabled)D0 D1 D2 D3 D4 D5 D6 D7 PStartbitStopbitTX pin output*RTS_ST(UA_MCR[13]),RTS pin output(default)Driver EnableNote: RS485_AUD(UA_ALT_CSR[10]) = 1, the RTS pin output by hardware control only.Figure 6.13-17 RS-485 RTS Driving Level in Auto Direction ModeThe following diagram demonstrates the RS-485 RTS driving level in software control(RS485_AUD(UA_ALT_CSR[10])=0). The RTS driving level is controlled by programing theRTS(UA_MCR[1]) control bit.Setting LEV_RTS(UA_MCR[9]) can control the RTS pin output is inverse or non-inverse fromRTS(UA_MCR[1]) control bit. User can read the RTS_ST(UA_MCR[13]) bit to get real RTS pinoutput voltage logic status.LEV_RTS = 0LEV_RTS = 1RTS pin output status of RS-485 function mode (RS-485 AUD mode enabled)D0 D1 D2 D3 D4 D5 D6 D7 PStartbitStopbitTX pin output*RTS_ST(UA_MCR[13]),RTS pin output(default)Driver EnableNote: RS485_AUD (UA_ALT_CSR[10]) = 0, support RTS control bit by software control only.Figure 6.13-18 RS-485 RTS Driving Level with Software ControlProgram Sequence Example:1. Program FUN_SEL in UA_FUN_SEL to select RS-485 function.2. Program the RX_DIS (UA_FCR[8]) to determine enable or disable the receiver RS-485receiver3. Program the RS485_NMM (UA_ALT_CSR[8]) or RS485_AAD (UA_ALT_CSR[9]) mode.4. If the RS485_AAD (UA_ALT_CSR[9]) mode is selected, the ADDR_MATCH(UA_ALT_CSR[31:24]) is programmed for auto address match value.
