From 1a89fde123e2acd63c57acfdb0b01d3dd1a1d0e1 Mon Sep 17 00:00:00 2001
From: Birger Koblitz <git@logicog.de>
Date: Mon, 4 Sep 2023 11:15:52 +0200
Subject: [PATCH] SPI: fix bug in csPin data type

The data type of the csPin member of spi_device_config was wrong.
The field will be set to -1 if no pin is set or manual cs-pin control is used.
Then the comparisons with -1 in the code will not work as expected, see
https://stackoverflow.com/questions/36770376/comparing-unsigned-char-to-a-negative-number

So we use "char" instead of "byte" and the code behaves as expected.
---
 src/SpiFirmata.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/SpiFirmata.h b/src/SpiFirmata.h
index f405d04..9300d09 100644
--- a/src/SpiFirmata.h
+++ b/src/SpiFirmata.h
@@ -40,7 +40,7 @@
 struct spi_device_config {
   byte deviceIdChannel;
   byte csPinOptions;
-  byte csPin;
+  char csPin;
   boolean packedData;
   SPISettings spi_settings;
   boolean used;