From 5ed0b37fedcd9fe10eb281d55b5a78ded7b950fe Mon Sep 17 00:00:00 2001
From: Juraj Andrassy <juraj.andrassy@gmail.com>
Date: Sat, 31 Aug 2019 17:06:32 +0200
Subject: [PATCH] option to deselect other device on SPI (for example network
 chip)

---
 Makefile  | 7 +++++++
 asmfunc.S | 8 ++++++++
 2 files changed, 15 insertions(+)

diff --git a/Makefile b/Makefile
index c986e90..f0b092d 100644
--- a/Makefile
+++ b/Makefile
@@ -9,6 +9,9 @@ F_CPU         = 16000000  # CPU clock frequency [Hz] NOT critical: it just shoul
 SD_CS_PORT    = PORTB # Data Register of the SD CS pin
 SD_CS_DDR     = DDRB # Data Direction Register of the SD CS pin
 SD_CS_BIT     = 4 # Bit of the SD CS pin
+#OTHER_CS_PORT = PORTD # Data Register of other SPI device CS pin
+#OTHER_CS_DDR  = DDRD # Data Direction Register of other SPI device CS pin
+#OTHER_CS_BIT  = 2 # Bit of other SPI device CS pin
 USE_LED       = 0 # Debug with two (defined in asmfunc.S)
 USE_UART      = 0 # Debug on Serial. 0 ... deactivate or divider of http://wormfood.net/avrbaudcalc.php for baud rate!
 #------------------------------------------------------------------
@@ -21,7 +24,11 @@ endif
 TARGET      = avr_boot
 ASRC        = asmfunc.S
 OPTIMIZE    = -Os -mcall-prologues -ffunction-sections -fdata-sections
+ifdef OTHER_CS_BIT
+DEFS        = -DBOOT_ADR=$(BOOT_ADR) -DF_CPU=$(F_CPU) -DUSE_LED=$(USE_LED) -DUSE_UART=$(USE_UART) -DSD_CS_PORT=$(SD_CS_PORT) -DSD_CS_DDR=$(SD_CS_DDR) -DSD_CS_BIT=$(SD_CS_BIT) -DOTHER_CS_PORT=$(OTHER_CS_PORT) -DOTHER_CS_DDR=$(OTHER_CS_DDR) -DOTHER_CS_BIT=$(OTHER_CS_BIT)
+else
 DEFS        = -DBOOT_ADR=$(BOOT_ADR) -DF_CPU=$(F_CPU) -DUSE_LED=$(USE_LED) -DUSE_UART=$(USE_UART) -DSD_CS_PORT=$(SD_CS_PORT) -DSD_CS_DDR=$(SD_CS_DDR) -DSD_CS_BIT=$(SD_CS_BIT)
+endif
 LIBS        =
 DEBUG       = dwarf-2
 
diff --git a/asmfunc.S b/asmfunc.S
index 6c09175..4e8b548 100644
--- a/asmfunc.S
+++ b/asmfunc.S
@@ -17,6 +17,11 @@
 #define	DDR_CS	_SFR_IO_ADDR(SD_CS_DDR), SD_CS_BIT
 #define	PORT_CS	_SFR_IO_ADDR(SD_CS_PORT), SD_CS_BIT
 
+;OTHER DEVICE CS PIN
+#ifdef OTHER_CS_BIT
+#define	DDR_CS1	_SFR_IO_ADDR(OTHER_CS_DDR), OTHER_CS_BIT
+#define	PORT_CS1 _SFR_IO_ADDR(OTHER_CS_PORT), OTHER_CS_BIT
+#endif
 ;---------------------------------------------------------------------------;
 .nolist
 #include <avr/io.h>
@@ -87,6 +92,9 @@ init_spi:
 	sbi	DDR_DI		; DI: output
 	sbi	DDR_CK		; SCLK: output
 	sbi	PORT_DO		; DO: pull-up
+#ifdef PORT_CS1
+	sbi	PORT_CS1	; CS1: pull-up
+#endif
 	ret
 .endfunc