953Chapter 20 Port FunctionsUser’s Manual U16580EE3V1UD0020.3.16 Port CSPort CS is a 4-bit I/O port that can be set to input or output mode in 1-bit units.(1) Functions• Input/output data can be specified in 1-bit units by using the port register CS (PCS).• Input or output mode can be set in 1-bit units by using the port mode register CS (PMCS).• Port mode or control mode (for alternate function) can be specified in 1-bit units by using theport mode control register CS (PMCCS).Table 20-19: Alternate Function Pins and Port Types of Port CSNote: Alternate function not available on μPD70F3447.Caution: On the μPD70F31187, in single-chip mode 1 or in ROM-less mode, this port has exter-nal control bus function only. Reprogramming of port CS to port mode is not possiblein these modes. Reading and writing of the port register PCS and port mode registerPMCS is possible but has no effect. Reading of the port mode control registerPMCCS is possible and the result is always 1BH. Writing of the port mode controlregister PMCCS is not possible.(2) Control registers(a) Port register CS (PCS)The PCS register is an 8-bit register that controls reading the pin levels and writing the outputlevels of port pins PCS0, PCS1, PCS3 and PCS4.This register can be read or written in 8-bit or 1-bit units.Reset input causes an undefined register content.Figure 20-70: Port Register CS (PCS)Remark: n = 0, 1, 3, 4Port Alternate Function Remark Port TypePort CS PCS0toPCS5CS0Note Chip select signal outputNote 1CS1NoteCS3NoteCS4NoteAfter reset: Undefined R/W Address: FFFFF008H7 6 5 4 3 2 1 0PCS 0 0 0 PCS4 PCS3 0 PCS1 PCS0PCSn Input/Output Data Control of Pin PCSn0 Input mode: Low level is inputOutput mode: Low level is output1 Input mode: High level is inputOutput mode: High level is output
